<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with Wdesk from Workiva-->
<!--Copyright 2022 Workiva-->
<!--r:a1a3dbf5-9808-4170-bbc4-402bc372a8dc,g:6668591b-65f8-40a2-85c1-3a9cf862f0a4-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:roleRef roleURI="http://www.pliantrx.com/role/Cover" xlink:type="simple" xlink:href="plrx-20220331.xsd#Cover"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_CoverAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_e1207a65-8687-4738-ad80-e9728d9bcce9" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentType"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentType_e1207a65-8687-4738-ad80-e9728d9bcce9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_4b221469-f676-40ac-a699-30f448037fe1" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentQuarterlyReport"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentQuarterlyReport_4b221469-f676-40ac-a699-30f448037fe1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_c2f84094-0c7a-4975-a7fa-2a8145519a3d" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentPeriodEndDate"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentPeriodEndDate_c2f84094-0c7a-4975-a7fa-2a8145519a3d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_67ea41a5-0443-49ba-be04-65abb6e9ddf8" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentTransitionReport"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentTransitionReport_67ea41a5-0443-49ba-be04-65abb6e9ddf8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_c569b0b0-6034-4a25-ad82-cd6a0921a04a" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityFileNumber"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityFileNumber_c569b0b0-6034-4a25-ad82-cd6a0921a04a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_68bac6cb-af05-411f-b5fe-3f45b540c2f1" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityRegistrantName"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityRegistrantName_68bac6cb-af05-411f-b5fe-3f45b540c2f1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_7623e724-4fe2-4651-b071-552c9abe1b8a" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityIncorporationStateCountryCode_7623e724-4fe2-4651-b071-552c9abe1b8a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_2328b78c-4f38-4033-89e0-9ca77661019e" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityTaxIdentificationNumber_2328b78c-4f38-4033-89e0-9ca77661019e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_0c8571ba-4b56-46cf-abb1-1026a721b7b2" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressAddressLine1"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityAddressAddressLine1_0c8571ba-4b56-46cf-abb1-1026a721b7b2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_6324eaab-e573-4d06-beef-5e2759476abb" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressCityOrTown"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityAddressCityOrTown_6324eaab-e573-4d06-beef-5e2759476abb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_cf46e2e9-08e6-4c47-bf63-2449d7e8a9b0" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressStateOrProvince"/>
    <link:presentationArc order="11" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityAddressStateOrProvince_cf46e2e9-08e6-4c47-bf63-2449d7e8a9b0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_b6258835-1460-42ce-8573-9570e290b9af" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityAddressPostalZipCode"/>
    <link:presentationArc order="12" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityAddressPostalZipCode_b6258835-1460-42ce-8573-9570e290b9af" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_15fd1fe5-5b16-43af-8af5-136ac1ea707b" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_CityAreaCode"/>
    <link:presentationArc order="13" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_CityAreaCode_15fd1fe5-5b16-43af-8af5-136ac1ea707b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_c8f7227e-8aca-4b61-bbcf-e3d3cac57ed4" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_LocalPhoneNumber"/>
    <link:presentationArc order="14" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_LocalPhoneNumber_c8f7227e-8aca-4b61-bbcf-e3d3cac57ed4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_9a7c0e2e-e70d-4655-85c7-d71d02e9b3c6" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_Security12bTitle"/>
    <link:presentationArc order="15" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_Security12bTitle_9a7c0e2e-e70d-4655-85c7-d71d02e9b3c6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_3ae615c6-441e-4a9d-8ac3-b8cbc01319a1" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_TradingSymbol"/>
    <link:presentationArc order="16" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_TradingSymbol_3ae615c6-441e-4a9d-8ac3-b8cbc01319a1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_80965c9a-d385-4676-871f-735bb08f645b" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_SecurityExchangeName"/>
    <link:presentationArc order="17" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_SecurityExchangeName_80965c9a-d385-4676-871f-735bb08f645b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_44965dbf-4af6-4882-9fe1-5ec308a237f4" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityCurrentReportingStatus"/>
    <link:presentationArc order="18" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityCurrentReportingStatus_44965dbf-4af6-4882-9fe1-5ec308a237f4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_4ee6cfc7-3898-48d8-a733-7294a65fac7c" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:presentationArc order="19" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityInteractiveDataCurrent_4ee6cfc7-3898-48d8-a733-7294a65fac7c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_1f751c7e-acd4-4bb6-bae0-4f674b04d379" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityFilerCategory"/>
    <link:presentationArc order="20" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityFilerCategory_1f751c7e-acd4-4bb6-bae0-4f674b04d379" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_77c6e593-3015-49a9-90eb-d78fb619d029" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntitySmallBusiness"/>
    <link:presentationArc order="21" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntitySmallBusiness_77c6e593-3015-49a9-90eb-d78fb619d029" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_3625fa22-5372-47ea-8b6d-d176260efea3" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:presentationArc order="22" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityEmergingGrowthCompany_3625fa22-5372-47ea-8b6d-d176260efea3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_15ba3458-9139-4300-945b-71ae5e4753f4" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityShellCompany"/>
    <link:presentationArc order="23" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityShellCompany_15ba3458-9139-4300-945b-71ae5e4753f4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_1d7666b1-16a9-4765-baa1-60af1b306bbb" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:presentationArc order="24" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_1d7666b1-16a9-4765-baa1-60af1b306bbb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_3f578e54-fe76-45e1-a097-c31a27d8e259" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_AmendmentFlag"/>
    <link:presentationArc order="25" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_AmendmentFlag_3f578e54-fe76-45e1-a097-c31a27d8e259" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_aafe312d-ddad-4fed-9e36-2d649c2ed38e" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentFiscalYearFocus"/>
    <link:presentationArc order="26" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentFiscalYearFocus_aafe312d-ddad-4fed-9e36-2d649c2ed38e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_acb8d98a-8c8c-47b4-a424-e6b07dcaf0f7" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:presentationArc order="27" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_DocumentFiscalPeriodFocus_acb8d98a-8c8c-47b4-a424-e6b07dcaf0f7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_af46efee-0f83-4219-9828-f75d85ddb8b2" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_EntityCentralIndexKey"/>
    <link:presentationArc order="28" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_EntityCentralIndexKey_af46efee-0f83-4219-9828-f75d85ddb8b2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_287ddd63-1139-4748-ad5f-e0dc22394c19" xlink:href="https://xbrl.sec.gov/dei/2021q4/dei-2021q4.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:presentationArc order="29" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_dei_CoverAbstract_5a26092e-89cc-4534-acf2-5548203ef5a7" xlink:to="loc_dei_CurrentFiscalYearEndDate_287ddd63-1139-4748-ad5f-e0dc22394c19" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CondensedBalanceSheetsUnaudited" xlink:type="simple" xlink:href="plrx-20220331.xsd#CondensedBalanceSheetsUnaudited"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CondensedBalanceSheetsUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_4bd1f0a9-8cd3-4e70-9fd6-34c620058068" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_4bd1f0a9-8cd3-4e70-9fd6-34c620058068" xlink:to="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:to="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_e2fe037c-da67-45a3-a2e3-5039233ff7d6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_e2fe037c-da67-45a3-a2e3-5039233ff7d6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_419b54a4-51c5-44f4-9c71-d49c63c269db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShortTermInvestments"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_ShortTermInvestments_419b54a4-51c5-44f4-9c71-d49c63c269db" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_204d0a91-3b39-4bd9-8293-0ba5759c34c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_204d0a91-3b39-4bd9-8293-0ba5759c34c1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesReceivable_51c8053b-6a8b-4611-9fbd-d87fe7c48c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxesReceivable"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_IncomeTaxesReceivable_51c8053b-6a8b-4611-9fbd-d87fe7c48c8f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_8eb95532-1e4b-4355-b9ae-15f17cae06ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_8eb95532-1e4b-4355-b9ae-15f17cae06ef" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_ab68d065-d173-45a6-aad2-bddcff4f1c7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AssetsCurrent"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsCurrentAbstract_c5fbe200-6061-4f30-9236-f20bf039019f" xlink:to="loc_us-gaap_AssetsCurrent_ab68d065-d173-45a6-aad2-bddcff4f1c7f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_3f160c45-97a9-43f2-a754-3779728bcbcf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_3f160c45-97a9-43f2-a754-3779728bcbcf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_e8f1c778-6d20-4ed4-a95b-e11ff0e6b444" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_e8f1c778-6d20-4ed4-a95b-e11ff0e6b444" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_1cf56491-87ae-4110-afa7-d53afbacf730" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_1cf56491-87ae-4110-afa7-d53afbacf730" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_67f94447-97a7-44a2-846d-c5eae24619a8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Assets"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AssetsAbstract_6d0318dd-831c-4c1f-870e-de291b94ef57" xlink:to="loc_us-gaap_Assets_67f94447-97a7-44a2-846d-c5eae24619a8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_4bd1f0a9-8cd3-4e70-9fd6-34c620058068" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_b453a08d-8594-436f-9b7d-bd66c1078d28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:to="loc_us-gaap_AccountsPayableCurrent_b453a08d-8594-436f-9b7d-bd66c1078d28" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_dd4a5d9e-44c4-4fdf-be4f-c64ed2ca770c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_dd4a5d9e-44c4-4fdf-be4f-c64ed2ca770c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_d6e6d230-b2c9-43ef-9fb0-55d8c63bf04b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_d6e6d230-b2c9-43ef-9fb0-55d8c63bf04b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_cfb5dc05-bd19-4e95-adb1-8a6d58d6d261" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_ecf0bac6-7994-4bc6-ad11-8d9741f38bb7" xlink:to="loc_us-gaap_LiabilitiesCurrent_cfb5dc05-bd19-4e95-adb1-8a6d58d6d261" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_bf6e5c54-fa7e-4880-9fd0-90c6b677a884" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_bf6e5c54-fa7e-4880-9fd0-90c6b677a884" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_475e579b-1e8d-4483-9621-50d0e2e4a63e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Liabilities"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:to="loc_us-gaap_Liabilities_475e579b-1e8d-4483-9621-50d0e2e4a63e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:to="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_43a07ce0-70eb-4cdb-a728-6e33abbe2208" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockValue"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:to="loc_us-gaap_CommonStockValue_43a07ce0-70eb-4cdb-a728-6e33abbe2208" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_74e06b85-e728-4729-9247-f1f6d5e77b7f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_74e06b85-e728-4729-9247-f1f6d5e77b7f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_324bb718-6207-432a-9168-d86c1901efe6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_324bb718-6207-432a-9168-d86c1901efe6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_cd0b18e0-b041-4ead-8786-b3276352f84d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_cd0b18e0-b041-4ead-8786-b3276352f84d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_205c4ff8-dae0-40af-9517-87088a027ea8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StockholdersEquityAbstract_7876082b-12f6-4149-8b18-b0e561fafeaa" xlink:to="loc_us-gaap_StockholdersEquity_205c4ff8-dae0-40af-9517-87088a027ea8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_6c528280-2e03-4756-942c-be03e7344135" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_a8e94c01-837c-4efc-a94a-f926869e6f4e" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_6c528280-2e03-4756-942c-be03e7344135" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CondensedBalanceSheetsUnauditedParenthetical" xlink:type="simple" xlink:href="plrx-20220331.xsd#CondensedBalanceSheetsUnauditedParenthetical"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CondensedBalanceSheetsUnauditedParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_7a2da380-6975-4800-8979-074caf9060c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_1e441661-c8b4-4628-82c9-ac2d9ef9ac42" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7a2da380-6975-4800-8979-074caf9060c8" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_1e441661-c8b4-4628-82c9-ac2d9ef9ac42" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_70ca10c2-2824-437f-97b9-baea76a75be7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7a2da380-6975-4800-8979-074caf9060c8" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_70ca10c2-2824-437f-97b9-baea76a75be7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_1264fc6b-3af2-48f3-8773-6d3c8608d05a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7a2da380-6975-4800-8979-074caf9060c8" xlink:to="loc_us-gaap_CommonStockSharesIssued_1264fc6b-3af2-48f3-8773-6d3c8608d05a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_25625693-87ee-43e1-aa14-d93709eeb725" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfFinancialPositionAbstract_7a2da380-6975-4800-8979-074caf9060c8" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_25625693-87ee-43e1-aa14-d93709eeb725" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CondensedStatementsofOperationsandComprehensiveIncomeLossUnaudited" xlink:type="simple" xlink:href="plrx-20220331.xsd#CondensedStatementsofOperationsandComprehensiveIncomeLossUnaudited"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CondensedStatementsofOperationsandComprehensiveIncomeLossUnaudited" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c8eb47b5-a266-4763-be99-761dd7cd517b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c8eb47b5-a266-4763-be99-761dd7cd517b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_4d17d466-13de-4720-aeda-dd970e9c5f30" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_OperatingExpensesAbstract_4d17d466-13de-4720-aeda-dd970e9c5f30" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_fc2988e2-a0fd-49cf-ac35-1791b0963ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_4d17d466-13de-4720-aeda-dd970e9c5f30" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_fc2988e2-a0fd-49cf-ac35-1791b0963ccd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_4b04a79c-624b-4240-af77-dfb06505eeb8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_4d17d466-13de-4720-aeda-dd970e9c5f30" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_4b04a79c-624b-4240-af77-dfb06505eeb8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_21a0fedd-b784-4949-8d42-412b1f330f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingExpenses"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingExpensesAbstract_4d17d466-13de-4720-aeda-dd970e9c5f30" xlink:to="loc_us-gaap_OperatingExpenses_21a0fedd-b784-4949-8d42-412b1f330f5a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedTotalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_a50a03bd-1dc1-492c-b3a9-acfd3a115650" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_OperatingIncomeLoss_a50a03bd-1dc1-492c-b3a9-acfd3a115650" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_InterestAndOtherIncomeNet_f64e7d89-1cf5-487d-b95c-a9add3bcc888" xlink:href="plrx-20220331.xsd#plrx_InterestAndOtherIncomeNet"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_plrx_InterestAndOtherIncomeNet_f64e7d89-1cf5-487d-b95c-a9add3bcc888" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_e7e4a489-3f34-4453-b000-5dc9f8a1b475" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_e7e4a489-3f34-4453-b000-5dc9f8a1b475" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_7f4fdae2-94e8-443c-a788-74df0cde2565" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_EarningsPerShareAbstract_7f4fdae2-94e8-443c-a788-74df0cde2565" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_7ab6dcac-5c96-4aab-9f17-de5bc545e63d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7f4fdae2-94e8-443c-a788-74df0cde2565" xlink:to="loc_us-gaap_EarningsPerShareBasic_7ab6dcac-5c96-4aab-9f17-de5bc545e63d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_cfa4c2be-bf16-4219-872d-34037570600e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7f4fdae2-94e8-443c-a788-74df0cde2565" xlink:to="loc_us-gaap_EarningsPerShareDiluted_cfa4c2be-bf16-4219-872d-34037570600e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_76d70d46-f011-485c-8e4c-221455ad5989" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_76d70d46-f011-485c-8e4c-221455ad5989" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_e75428d7-1107-4a21-847e-120f67a1d397" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_76d70d46-f011-485c-8e4c-221455ad5989" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_e75428d7-1107-4a21-847e-120f67a1d397" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6d1ecfee-8865-40b0-ac18-804f25f07b47" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_76d70d46-f011-485c-8e4c-221455ad5989" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_6d1ecfee-8865-40b0-ac18-804f25f07b47" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTaxAbstract"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementAbstract_75b9193e-520e-45b6-9218-be28db757f73" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_e4b05caf-cc0b-45a0-a869-07724277b92f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:to="loc_us-gaap_NetIncomeLoss_e4b05caf-cc0b-45a0-a869-07724277b92f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_fe76663c-2e68-4aff-82ad-8e46fd71a28a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_fe76663c-2e68-4aff-82ad-8e46fd71a28a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_80d6ec1d-8e1d-4530-9486-e0ddfa8fa2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_80d6ec1d-8e1d-4530-9486-e0ddfa8fa2eb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_0a1e677f-a419-493f-8140-827b7ac7ad6e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTaxAbstract_402277e1-652e-4d24-ac06-8e54ec5b7eb3" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_0a1e677f-a419-493f-8140-827b7ac7ad6e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CondensedStatementsofStockholdersEquity" xlink:type="simple" xlink:href="plrx-20220331.xsd#CondensedStatementsofStockholdersEquity"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CondensedStatementsofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract_22bb20bd-790e-42d6-b8c9-2eadfc3b5920" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfStockholdersEquityAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_d0c4a19a-4dda-4a7c-a152-7a02431e905d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfStockholdersEquityAbstract_22bb20bd-790e-42d6-b8c9-2eadfc3b5920" xlink:to="loc_us-gaap_StatementTable_d0c4a19a-4dda-4a7c-a152-7a02431e905d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_aba9c49b-c791-4c08-9660-22d316d8f246" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementTable_d0c4a19a-4dda-4a7c-a152-7a02431e905d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_aba9c49b-c791-4c08-9660-22d316d8f246" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityComponentDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_aba9c49b-c791-4c08-9660-22d316d8f246" xlink:to="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_3529291d-679b-4c4a-8e50-d87e9c891c92" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:to="loc_us-gaap_CommonStockMember_3529291d-679b-4c4a-8e50-d87e9c891c92" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_2792394c-c381-42af-a8b2-ffc5e2ffaef3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_2792394c-c381-42af-a8b2-ffc5e2ffaef3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_21f5cd64-7ff1-4f48-b668-63de69c59280" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_21f5cd64-7ff1-4f48-b668-63de69c59280" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_60fc7cde-2464-4c2e-b3b7-c7a2cd4ae0bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RetainedEarningsMember"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityComponentDomain_768a8ab0-9df9-4502-928d-2679ceac5068" xlink:to="loc_us-gaap_RetainedEarningsMember_60fc7cde-2464-4c2e-b3b7-c7a2cd4ae0bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_66de2913-a712-4add-be28-b114c7623a59" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementTable_d0c4a19a-4dda-4a7c-a152-7a02431e905d" xlink:to="loc_us-gaap_StatementLineItems_66de2913-a712-4add-be28-b114c7623a59" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementLineItems_66de2913-a712-4add-be28-b114c7623a59" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_49338e00-8e19-4645-9a18-78151ca13b04" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_49338e00-8e19-4645-9a18-78151ca13b04" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_bd01f837-ade7-4086-b1d4-43b619fd7be3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockholdersEquity_bd01f837-ade7-4086-b1d4-43b619fd7be3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_0b7eb0fa-2430-4227-89be-b54e2330541d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_0b7eb0fa-2430-4227-89be-b54e2330541d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_a4aa4f25-4a13-4ca2-83a5-ca21c5b10bc9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_a4aa4f25-4a13-4ca2-83a5-ca21c5b10bc9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a6adfa70-8279-45e2-ad81-98c7ff40a8e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a6adfa70-8279-45e2-ad81-98c7ff40a8e0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_1d990c4b-7235-4a32-a66c-718118118d14" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_1d990c4b-7235-4a32-a66c-718118118d14" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_f7a0c785-3c72-4b2a-97ab-df9b1c7b3f7a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_f7a0c785-3c72-4b2a-97ab-df9b1c7b3f7a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_10a388c7-9ced-4673-b430-f08d7ec7f5e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_10a388c7-9ced-4673-b430-f08d7ec7f5e1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_bc9e7c8d-d9e0-4a91-b70d-783538edb6fd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_NetIncomeLoss_bc9e7c8d-d9e0-4a91-b70d-783538edb6fd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_1e8bbfb9-ce22-4cea-986c-cd264c1c7a3e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_1e8bbfb9-ce22-4cea-986c-cd264c1c7a3e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_f6dcff93-6cc1-411a-981b-fb430d7d82d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquity"/>
    <link:presentationArc order="11" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_7d4ac4c0-7720-4e9e-b600-b73883e92d9c" xlink:to="loc_us-gaap_StockholdersEquity_f6dcff93-6cc1-411a-981b-fb430d7d82d7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CondensedStatementsofCashFlows" xlink:type="simple" xlink:href="plrx-20220331.xsd#CondensedStatementsofCashFlows"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CondensedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c22ecb76-287e-40e5-9c73-25d5cd4263b4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c22ecb76-287e-40e5-9c73-25d5cd4263b4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_793ff058-1554-4a07-81eb-a302d1e3a3c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c22ecb76-287e-40e5-9c73-25d5cd4263b4" xlink:to="loc_us-gaap_NetIncomeLoss_793ff058-1554-4a07-81eb-a302d1e3a3c1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c22ecb76-287e-40e5-9c73-25d5cd4263b4" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_574d3acd-2964-48bf-864f-2e17b2d4e5da" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Depreciation"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:to="loc_us-gaap_Depreciation_574d3acd-2964-48bf-864f-2e17b2d4e5da" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_53a3fc8c-bff9-4d59-91c3-249d1be3a7df" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensation"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:to="loc_us-gaap_ShareBasedCompensation_53a3fc8c-bff9-4d59-91c3-249d1be3a7df" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_3b17531b-ae8d-451d-a5ca-5a8eda8790e7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_3b17531b-ae8d-451d-a5ca-5a8eda8790e7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_OtherLosses_61488245-950b-4b83-93fb-84c9adf083ea" xlink:href="plrx-20220331.xsd#plrx_OtherLosses"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:to="loc_plrx_OtherLosses_61488245-950b-4b83-93fb-84c9adf083ea" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_7fc23556-62cf-4753-a927-9fb0a0ee42d3" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_dd60a44c-5656-46cf-bf95-29d49fe49f7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_dd60a44c-5656-46cf-bf95-29d49fe49f7b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_d114f47f-cc84-472e-a273-4fada2ca8ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_d114f47f-cc84-472e-a273-4fada2ca8ba5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_0dc5fac1-7f61-43a7-ba76-b5fedba10fb3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_0dc5fac1-7f61-43a7-ba76-b5fedba10fb3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_c9ecefd5-dc37-400a-b91f-f079467d43f3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_c9ecefd5-dc37-400a-b91f-f079467d43f3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_bf1ac7fd-324d-44cc-98ac-df2912e34bd4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedLiabilities_bf1ac7fd-324d-44cc-98ac-df2912e34bd4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_fbc7e4e9-29a1-4b6f-b78e-fa4c182f0b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncreaseDecreaseInOperatingLeaseLiability"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_a3e173d2-2a4a-42a6-8b4f-5ae318a958bf" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingLeaseLiability_fbc7e4e9-29a1-4b6f-b78e-fa4c182f0b9d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_5503007a-2a77-40d3-a27e-b7bda7b27b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_c22ecb76-287e-40e5-9c73-25d5cd4263b4" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_5503007a-2a77-40d3-a27e-b7bda7b27b2b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireShortTermInvestments_55f5bbcc-8d04-4d09-bfdf-00625e0c579a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquireShortTermInvestments"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:to="loc_us-gaap_PaymentsToAcquireShortTermInvestments_55f5bbcc-8d04-4d09-bfdf-00625e0c579a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments_79930e17-97c4-4854-af1b-3e423240f792" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:to="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfShorttermInvestments_79930e17-97c4-4854-af1b-3e423240f792" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_b4413cd3-f9ef-43a6-a3d7-4198605e3d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_b4413cd3-f9ef-43a6-a3d7-4198605e3d5e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_bbbf23bc-8097-40be-b75e-09484ae20108" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_f92f9e99-63c1-4cb6-87c7-331b1634aae3" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_bbbf23bc-8097-40be-b75e-09484ae20108" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_03186751-e88e-44d8-8e8a-05c864a48f18" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_03186751-e88e-44d8-8e8a-05c864a48f18" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_db548556-2341-4be5-bb49-533095923f30" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_03186751-e88e-44d8-8e8a-05c864a48f18" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_db548556-2341-4be5-bb49-533095923f30" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PaymentsOfDeferredOfferingCosts_1d616c30-11f9-4f23-adbf-46270b24dca9" xlink:href="plrx-20220331.xsd#plrx_PaymentsOfDeferredOfferingCosts"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_03186751-e88e-44d8-8e8a-05c864a48f18" xlink:to="loc_plrx_PaymentsOfDeferredOfferingCosts_1d616c30-11f9-4f23-adbf-46270b24dca9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_9eaf59d1-d330-4d6e-a4da-4a398309d079" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_03186751-e88e-44d8-8e8a-05c864a48f18" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_9eaf59d1-d330-4d6e-a4da-4a398309d079" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_99f309f5-cb04-48a6-b93d-74d050ddd8e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_99f309f5-cb04-48a6-b93d-74d050ddd8e1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_fff8b611-d0de-400c-a4ba-736a9e5804ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_fff8b611-d0de-400c-a4ba-736a9e5804ea" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_c204743a-7248-4140-8574-a21945b4c4bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_c204743a-7248-4140-8574-a21945b4c4bc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalCashFlowElementsAbstract_e53590d6-dc78-46c2-a847-8ceb6c3090e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SupplementalCashFlowElementsAbstract"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementOfCashFlowsAbstract_94e91b25-df87-4b82-97b3-bbb518fa8683" xlink:to="loc_us-gaap_SupplementalCashFlowElementsAbstract_e53590d6-dc78-46c2-a847-8ceb6c3090e3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PurchasesOfPropertyAndEquipmentIncludedInAccountsPayableAndAccruedLiabilities_e386c25e-eef4-4ff2-8f5d-8beecb9da2dc" xlink:href="plrx-20220331.xsd#plrx_PurchasesOfPropertyAndEquipmentIncludedInAccountsPayableAndAccruedLiabilities"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SupplementalCashFlowElementsAbstract_e53590d6-dc78-46c2-a847-8ceb6c3090e3" xlink:to="loc_plrx_PurchasesOfPropertyAndEquipmentIncludedInAccountsPayableAndAccruedLiabilities_e386c25e-eef4-4ff2-8f5d-8beecb9da2dc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ReclassificationOfRestrictedStockAwardsFromLiabilitiesToCommonStockUponVesting_ef0edef7-ddd4-4407-9cda-d2342fad48b8" xlink:href="plrx-20220331.xsd#plrx_ReclassificationOfRestrictedStockAwardsFromLiabilitiesToCommonStockUponVesting"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SupplementalCashFlowElementsAbstract_e53590d6-dc78-46c2-a847-8ceb6c3090e3" xlink:to="loc_plrx_ReclassificationOfRestrictedStockAwardsFromLiabilitiesToCommonStockUponVesting_ef0edef7-ddd4-4407-9cda-d2342fad48b8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments_f8dde380-7d50-42b9-9678-9bf581cde7a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SupplementalCashFlowElementsAbstract_e53590d6-dc78-46c2-a847-8ceb6c3090e3" xlink:to="loc_us-gaap_UnrealizedGainLossOnInvestments_f8dde380-7d50-42b9-9678-9bf581cde7a4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/OrganizationandDescriptionofBusiness" xlink:type="simple" xlink:href="plrx-20220331.xsd#OrganizationandDescriptionofBusiness"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/OrganizationandDescriptionofBusiness" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_88707a52-dc3c-41e9-b152-de81c84a38c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock_a2e3338a-9835-4208-ad3a-814949db1189" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_88707a52-dc3c-41e9-b152-de81c84a38c5" xlink:to="loc_us-gaap_BusinessDescriptionAndBasisOfPresentationTextBlock_a2e3338a-9835-4208-ad3a-814949db1189" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/SummaryofSignificantAccountingPolicies" xlink:type="simple" xlink:href="plrx-20220331.xsd#SummaryofSignificantAccountingPolicies"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/SummaryofSignificantAccountingPolicies" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_102cc3e0-4c18-4157-99cf-552b3f6c9d5f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingPoliciesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock_552d381a-51ec-4ff5-8ef7-bdeff84ffc3d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_102cc3e0-4c18-4157-99cf-552b3f6c9d5f" xlink:to="loc_us-gaap_SignificantAccountingPoliciesTextBlock_552d381a-51ec-4ff5-8ef7-bdeff84ffc3d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/SummaryofSignificantAccountingPoliciesPolicies" xlink:type="simple" xlink:href="plrx-20220331.xsd#SummaryofSignificantAccountingPoliciesPolicies"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/SummaryofSignificantAccountingPoliciesPolicies" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingPoliciesAbstract_ed1b7ae2-5a49-4885-aea0-c2ec49486076" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountingPoliciesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_ad27b169-98af-4eeb-8028-abb064e8129b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BasisOfAccountingPolicyPolicyTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_ed1b7ae2-5a49-4885-aea0-c2ec49486076" xlink:to="loc_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_ad27b169-98af-4eeb-8028-abb064e8129b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UseOfEstimates_0fc28f6b-f011-4c79-aa3a-b5eb6e8dbaaf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_UseOfEstimates"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccountingPoliciesAbstract_ed1b7ae2-5a49-4885-aea0-c2ec49486076" xlink:to="loc_us-gaap_UseOfEstimates_0fc28f6b-f011-4c79-aa3a-b5eb6e8dbaaf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/FinancialInstruments" xlink:type="simple" xlink:href="plrx-20220331.xsd#FinancialInstruments"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/FinancialInstruments" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract_64561fe5-8028-4071-afd6-1638c8a12287" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosuresAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosuresTextBlock_d179d4d7-0b6e-4c86-b41f-43565788796f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosuresTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract_64561fe5-8028-4071-afd6-1638c8a12287" xlink:to="loc_us-gaap_FairValueDisclosuresTextBlock_d179d4d7-0b6e-4c86-b41f-43565788796f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/FinancialInstrumentsTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#FinancialInstrumentsTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/FinancialInstrumentsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract_a26ad700-b711-437c-83c6-41b0503b24ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosuresAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock_3a6ada3f-ff40-4300-ad3a-30b6050a46a9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract_a26ad700-b711-437c-83c6-41b0503b24ca" xlink:to="loc_us-gaap_ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock_3a6ada3f-ff40-4300-ad3a-30b6050a46a9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/FinancialInstrumentsSummaryofCashandCashEquivalentsMoneyMarketFundsandShorttermInvestmentsbySignificantInvestmentCategoryDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#FinancialInstrumentsSummaryofCashandCashEquivalentsMoneyMarketFundsandShorttermInvestmentsbySignificantInvestmentCategoryDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/FinancialInstrumentsSummaryofCashandCashEquivalentsMoneyMarketFundsandShorttermInvestmentsbySignificantInvestmentCategoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract_eabdc879-8301-480a-95a8-44ceb2442c02" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosuresAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract_eabdc879-8301-480a-95a8-44ceb2442c02" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_901df386-5c99-4e28-9542-3443b033ee2c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_901df386-5c99-4e28-9542-3443b033ee2c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_61cb2971-db29-4541-a13f-02a6b1f7dd54" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_901df386-5c99-4e28-9542-3443b033ee2c" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_61cb2971-db29-4541-a13f-02a6b1f7dd54" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_033af981-6426-47f0-b43e-7392fd0b8769" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_61cb2971-db29-4541-a13f-02a6b1f7dd54" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_033af981-6426-47f0-b43e-7392fd0b8769" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_902c4c54-a4dc-44cb-84ef-5820dc677b2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_61cb2971-db29-4541-a13f-02a6b1f7dd54" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_902c4c54-a4dc-44cb-84ef-5820dc677b2e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_a4032557-2492-4638-a20f-fc4d5d035667" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_a4032557-2492-4638-a20f-fc4d5d035667" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f933158e-a4a8-4278-9024-c03fb775db43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_a4032557-2492-4638-a20f-fc4d5d035667" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f933158e-a4a8-4278-9024-c03fb775db43" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_ee0142d5-6116-4dbf-b8eb-9aae3a228c28" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f933158e-a4a8-4278-9024-c03fb775db43" xlink:to="loc_us-gaap_MoneyMarketFundsMember_ee0142d5-6116-4dbf-b8eb-9aae3a228c28" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember_81218634-bedb-4a6b-ab37-8279c2c948b9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_f933158e-a4a8-4278-9024-c03fb775db43" xlink:to="loc_us-gaap_USGovernmentCorporationsAndAgenciesSecuritiesMember_81218634-bedb-4a6b-ab37-8279c2c948b9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeAxis_23e6d97d-aa82-4de1-b59b-f925319a45cb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentTypeAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:to="loc_us-gaap_InvestmentTypeAxis_23e6d97d-aa82-4de1-b59b-f925319a45cb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_a3e5af3e-9422-4330-b128-b9341ac2fa79" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InvestmentTypeAxis_23e6d97d-aa82-4de1-b59b-f925319a45cb" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_a3e5af3e-9422-4330-b128-b9341ac2fa79" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_fb7c4351-b63b-45a4-a2ba-76a6e14a7231" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_a3e5af3e-9422-4330-b128-b9341ac2fa79" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_fb7c4351-b63b-45a4-a2ba-76a6e14a7231" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_d1a4d37e-309b-43ad-acf7-8317b4b1e513" xlink:to="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_7a2d679f-0b1f-4a69-a2d8-c0ab20a657bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_7a2d679f-0b1f-4a69-a2d8-c0ab20a657bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_396aaaa7-ee8a-4d22-b337-5a745eb85215" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedGain_396aaaa7-ee8a-4d22-b337-5a745eb85215" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_7afd3ec0-7d4b-4f66-8acd-0e2884bb2696" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesGrossUnrealizedLoss_7afd3ec0-7d4b-4f66-8acd-0e2884bb2696" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_97bc9026-9559-4f91-ace8-05a47e54b855" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_984e3050-8fd2-490d-9753-7eece1db31e1" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_97bc9026-9559-4f91-ace8-05a47e54b855" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/FinancialInstrumentsNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#FinancialInstrumentsNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/FinancialInstrumentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosuresAbstract_c84c5abf-8313-4857-9b80-b78145bc2529" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueDisclosuresAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_c91b6ff7-e2d1-44f6-a09f-b1d5e489292e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueDisclosuresAbstract_c84c5abf-8313-4857-9b80-b78145bc2529" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_c91b6ff7-e2d1-44f6-a09f-b1d5e489292e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_dfdd3741-c950-48ca-b14d-d9028f283125" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_c91b6ff7-e2d1-44f6-a09f-b1d5e489292e" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_dfdd3741-c950-48ca-b14d-d9028f283125" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_48fab78b-5bb5-43dc-b8c1-293182b5e0d9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_dfdd3741-c950-48ca-b14d-d9028f283125" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_48fab78b-5bb5-43dc-b8c1-293182b5e0d9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_6cd6a0d0-14f3-4b87-beb8-077fb5dd421e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_48fab78b-5bb5-43dc-b8c1-293182b5e0d9" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_6cd6a0d0-14f3-4b87-beb8-077fb5dd421e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_dfff0c6f-4e5b-4ea7-b49f-4e9de9cb50dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueMeasurementsNonrecurringMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_48fab78b-5bb5-43dc-b8c1-293182b5e0d9" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_dfff0c6f-4e5b-4ea7-b49f-4e9de9cb50dd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_573c48f0-8f69-4731-833a-16e7270bbfe6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_c91b6ff7-e2d1-44f6-a09f-b1d5e489292e" xlink:to="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_573c48f0-8f69-4731-833a-16e7270bbfe6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_07c3a401-a0b1-4ac3-8415-c28f3d60f614" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_573c48f0-8f69-4731-833a-16e7270bbfe6" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_07c3a401-a0b1-4ac3-8415-c28f3d60f614" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount_6e2f815e-00bb-4228-95f3-96e2e982a58c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_573c48f0-8f69-4731-833a-16e7270bbfe6" xlink:to="loc_us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount_6e2f815e-00bb-4228-95f3-96e2e982a58c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PropertyandEquipmentnet" xlink:type="simple" xlink:href="plrx-20220331.xsd#PropertyandEquipmentnet"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PropertyandEquipmentnet" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_a292017b-cd5b-4665-86c0-6b32b6c1e320" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_8d18edd4-c749-466b-b660-c93e42438182" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_a292017b-cd5b-4665-86c0-6b32b6c1e320" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentDisclosureTextBlock_8d18edd4-c749-466b-b660-c93e42438182" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PropertyandEquipmentnetTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#PropertyandEquipmentnetTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PropertyandEquipmentnetTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_7ca2275a-f29e-48ef-ab36-a99048eb84c7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTextBlock_ca6d2082-9d2e-44eb-8375-6a8995314bed" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_7ca2275a-f29e-48ef-ab36-a99048eb84c7" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTextBlock_ca6d2082-9d2e-44eb-8375-6a8995314bed" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PropertyandEquipmentnetScheduleofPropertyandEquipmentDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#PropertyandEquipmentnetScheduleofPropertyandEquipmentDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PropertyandEquipmentnetScheduleofPropertyandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_9f7da7df-d5a0-48b1-bde3-4b7ee260caaf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35b6bcf5-6525-4e4c-bad8-a95df99a399c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_9f7da7df-d5a0-48b1-bde3-4b7ee260caaf" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35b6bcf5-6525-4e4c-bad8-a95df99a399c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_952dc0fa-8f86-4663-a45a-e21267268b29" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35b6bcf5-6525-4e4c-bad8-a95df99a399c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_952dc0fa-8f86-4663-a45a-e21267268b29" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_952dc0fa-8f86-4663-a45a-e21267268b29" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ComputerEquipmentAndSoftwareMember_2f53b6ea-5c78-403c-87b7-849d36822b4c" xlink:href="plrx-20220331.xsd#plrx_ComputerEquipmentAndSoftwareMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:to="loc_plrx_ComputerEquipmentAndSoftwareMember_2f53b6ea-5c78-403c-87b7-849d36822b4c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquipmentMember_ae64565a-278e-428b-a58e-17c4d015a65a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquipmentMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:to="loc_us-gaap_EquipmentMember_ae64565a-278e-428b-a58e-17c4d015a65a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_4fb8d81a-4bff-4494-9a36-bda98ab46f50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_4fb8d81a-4bff-4494-9a36-bda98ab46f50" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_5da59680-5507-4835-b6d6-a32617760798" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8504c735-42de-42ed-94bd-c4705111782c" xlink:to="loc_us-gaap_ConstructionInProgressMember_5da59680-5507-4835-b6d6-a32617760798" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_96cb8f51-50a3-45a1-90ef-38e0b7fcb043" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_35b6bcf5-6525-4e4c-bad8-a95df99a399c" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentLineItems_96cb8f51-50a3-45a1-90ef-38e0b7fcb043" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_8ca482ed-a135-4d1f-a812-8acc11abff39" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_96cb8f51-50a3-45a1-90ef-38e0b7fcb043" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_8ca482ed-a135-4d1f-a812-8acc11abff39" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_96b469fb-30fc-42a0-920a-e04339851356" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_96cb8f51-50a3-45a1-90ef-38e0b7fcb043" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_96b469fb-30fc-42a0-920a-e04339851356" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_55d88d8e-5c5b-4ae8-af63-5bfab39e86ef" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_96cb8f51-50a3-45a1-90ef-38e0b7fcb043" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_55d88d8e-5c5b-4ae8-af63-5bfab39e86ef" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PropertyandEquipmentnetNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#PropertyandEquipmentnetNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PropertyandEquipmentnetNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAbstract_fd012e49-60a4-4a40-b072-ca4f3f7cfd21" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PropertyPlantAndEquipmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_d8cbabc4-bde4-4bc4-8052-95048709fe2b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_Depreciation"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentAbstract_fd012e49-60a4-4a40-b072-ca4f3f7cfd21" xlink:to="loc_us-gaap_Depreciation_d8cbabc4-bde4-4bc4-8052-95048709fe2b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssets" xlink:type="simple" xlink:href="plrx-20220331.xsd#PrepaidExpensesandOtherCurrentAssets"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssets" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_f8162ca5-afe1-4377-ab07-8d85ed28a5c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PrepaidExpensesAndOtherCurrentAssetsTextBlock_34b603c9-48fd-4a4f-af7e-6002b5237505" xlink:href="plrx-20220331.xsd#plrx_PrepaidExpensesAndOtherCurrentAssetsTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_f8162ca5-afe1-4377-ab07-8d85ed28a5c2" xlink:to="loc_plrx_PrepaidExpensesAndOtherCurrentAssetsTextBlock_34b603c9-48fd-4a4f-af7e-6002b5237505" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssetsTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#PrepaidExpensesandOtherCurrentAssetsTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssetsTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_10c1569c-e7a4-4343-818e-0aa041892c2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ScheduleOfPrepaidExpensesAndOtherCurrentAssetsTableTextBlock_038ffbfe-4bae-4b26-9cde-cba0fab8f247" xlink:href="plrx-20220331.xsd#plrx_ScheduleOfPrepaidExpensesAndOtherCurrentAssetsTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_10c1569c-e7a4-4343-818e-0aa041892c2e" xlink:to="loc_plrx_ScheduleOfPrepaidExpensesAndOtherCurrentAssetsTableTextBlock_038ffbfe-4bae-4b26-9cde-cba0fab8f247" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssetsDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#PrepaidExpensesandOtherCurrentAssetsDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/PrepaidExpensesandOtherCurrentAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PrepaidResearchAndDevelopmentCurrent_27e6755c-e7b1-463a-b323-f901a4424f23" xlink:href="plrx-20220331.xsd#plrx_PrepaidResearchAndDevelopmentCurrent"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_plrx_PrepaidResearchAndDevelopmentCurrent_27e6755c-e7b1-463a-b323-f901a4424f23" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidInsurance_214f2b7c-dce6-441f-98a3-b5e986256419" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PrepaidInsurance"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_us-gaap_PrepaidInsurance_214f2b7c-dce6-441f-98a3-b5e986256419" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PrepaidLicensesCurrent_da251861-fdaf-49c9-9384-043a67326af4" xlink:href="plrx-20220331.xsd#plrx_PrepaidLicensesCurrent"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_plrx_PrepaidLicensesCurrent_da251861-fdaf-49c9-9384-043a67326af4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivableCurrent_3eae1039-ec4c-4cac-9bc1-a0cd81fe2cd9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_InterestReceivableCurrent"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_us-gaap_InterestReceivableCurrent_3eae1039-ec4c-4cac-9bc1-a0cd81fe2cd9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherPrepaidExpenseCurrent_fe01cdaa-791d-4e75-9629-61fac048a6d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherPrepaidExpenseCurrent"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_us-gaap_OtherPrepaidExpenseCurrent_fe01cdaa-791d-4e75-9629-61fac048a6d2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_9862b7e8-be42-4b43-93ac-57557064395f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DeferredCostsCapitalizedPrepaidAndOtherAssetsDisclosureAbstract_28efc9ec-ce36-46d0-845e-bc6d20219b65" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_9862b7e8-be42-4b43-93ac-57557064395f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilities" xlink:type="simple" xlink:href="plrx-20220331.xsd#AccruedLiabilitiesandOtherLongTermLiabilities"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilities" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_11c8bc20-101a-4489-a460-d62b92618d54" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock_d7208962-5748-4eda-be64-3b8794f17000" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_11c8bc20-101a-4489-a460-d62b92618d54" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesDisclosureTextBlock_d7208962-5748-4eda-be64-3b8794f17000" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilitiesTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#AccruedLiabilitiesandOtherLongTermLiabilitiesTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilitiesTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_d0f969ac-b468-4837-b86e-7095f5b71954" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_6ecfe119-8bbc-40da-a5c6-376ccaf9da58" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_d0f969ac-b468-4837-b86e-7095f5b71954" xlink:to="loc_us-gaap_ScheduleOfAccruedLiabilitiesTableTextBlock_6ecfe119-8bbc-40da-a5c6-376ccaf9da58" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilitiesSummaryofAccruedLiabilitiesDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#AccruedLiabilitiesandOtherLongTermLiabilitiesSummaryofAccruedLiabilitiesDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/AccruedLiabilitiesandOtherLongTermLiabilitiesSummaryofAccruedLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_65f026e1-7a1d-41bd-a19d-b447771ae51f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_d4bdb664-270c-42c4-988b-70b1229878ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_65f026e1-7a1d-41bd-a19d-b447771ae51f" xlink:to="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_d4bdb664-270c-42c4-988b-70b1229878ba" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_AccruedResearchAndDevelopmentExpensesCurrent_eb5d7da7-c16f-4b41-b79d-91c490f119af" xlink:href="plrx-20220331.xsd#plrx_AccruedResearchAndDevelopmentExpensesCurrent"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_65f026e1-7a1d-41bd-a19d-b447771ae51f" xlink:to="loc_plrx_AccruedResearchAndDevelopmentExpensesCurrent_eb5d7da7-c16f-4b41-b79d-91c490f119af" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_01a7bbed-fdcd-4ec7-bf63-47c0ac07928a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_65f026e1-7a1d-41bd-a19d-b447771ae51f" xlink:to="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_01a7bbed-fdcd-4ec7-bf63-47c0ac07928a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_fd2c126d-4517-4a71-a065-8ed127197edc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AccruedLiabilitiesAndOtherLiabilitiesAbstract_65f026e1-7a1d-41bd-a19d-b447771ae51f" xlink:to="loc_us-gaap_AccruedLiabilitiesCurrent_fd2c126d-4517-4a71-a065-8ed127197edc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreement" xlink:type="simple" xlink:href="plrx-20220331.xsd#NovartisCollaborationandLicenseAgreementtheNovartisAgreement"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_050e78b4-a6f4-4024-9757-302e9d8f335a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementDisclosureTextBlock_b670ddb7-732b-4f22-a4cd-dde7bda398bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CollaborativeArrangementDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_050e78b4-a6f4-4024-9757-302e9d8f335a" xlink:to="loc_us-gaap_CollaborativeArrangementDisclosureTextBlock_b670ddb7-732b-4f22-a4cd-dde7bda398bd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#NovartisCollaborationandLicenseAgreementtheNovartisAgreementNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_6f9b0754-7cea-4d99-8a1d-16e5eed0e80f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_6f9b0754-7cea-4d99-8a1d-16e5eed0e80f" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_7d4b9521-e781-4b4b-bcd7-3741c24968f7" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_srt_RangeAxis_7d4b9521-e781-4b4b-bcd7-3741c24968f7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9822484c-c13c-4336-8708-ebc6cba2cea4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeAxis_7d4b9521-e781-4b4b-bcd7-3741c24968f7" xlink:to="loc_srt_RangeMember_9822484c-c13c-4336-8708-ebc6cba2cea4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_c9e84459-540a-486c-bc3b-ebfe67a3a11f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_9822484c-c13c-4336-8708-ebc6cba2cea4" xlink:to="loc_srt_MaximumMember_c9e84459-540a-486c-bc3b-ebfe67a3a11f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_793170a1-f760-4bea-9684-c894c239a4be" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_793170a1-f760-4bea-9684-c894c239a4be" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_89acc363-9c36-4391-961b-d67d49579d1c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_793170a1-f760-4bea-9684-c894c239a4be" xlink:to="loc_us-gaap_RelatedPartyDomain_89acc363-9c36-4391-961b-d67d49579d1c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisMember_053d48e3-d544-4624-b56a-f1e371a84260" xlink:href="plrx-20220331.xsd#plrx_NovartisMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyDomain_89acc363-9c36-4391-961b-d67d49579d1c" xlink:to="loc_plrx_NovartisMember_053d48e3-d544-4624-b56a-f1e371a84260" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_78e9109a-60a4-4dc0-9392-a09b70146dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_us-gaap_TypeOfArrangementAxis_78e9109a-60a4-4dc0-9392-a09b70146dd6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_029dbec8-fd76-4234-b917-1b4abdb19c83" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TypeOfArrangementAxis_78e9109a-60a4-4dc0-9392-a09b70146dd6" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_029dbec8-fd76-4234-b917-1b4abdb19c83" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisAgreementMember_0259d6d6-db73-4383-b6b5-6655c88e9b5c" xlink:href="plrx-20220331.xsd#plrx_NovartisAgreementMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_029dbec8-fd76-4234-b917-1b4abdb19c83" xlink:to="loc_plrx_NovartisAgreementMember_0259d6d6-db73-4383-b6b5-6655c88e9b5c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisAgreementRDForPLN1474Member_28bfabee-21b8-4929-ab8b-fbc7cffa1d2f" xlink:href="plrx-20220331.xsd#plrx_NovartisAgreementRDForPLN1474Member"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_029dbec8-fd76-4234-b917-1b4abdb19c83" xlink:to="loc_plrx_NovartisAgreementRDForPLN1474Member_28bfabee-21b8-4929-ab8b-fbc7cffa1d2f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisAgreementRDForIntegrinResearchTargetsMember_34b6956a-d44d-49c3-b78a-a8fbbb031674" xlink:href="plrx-20220331.xsd#plrx_NovartisAgreementRDForIntegrinResearchTargetsMember"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_029dbec8-fd76-4234-b917-1b4abdb19c83" xlink:to="loc_plrx_NovartisAgreementRDForIntegrinResearchTargetsMember_34b6956a-d44d-49c3-b78a-a8fbbb031674" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_133e9574-d94f-4a53-a827-afc4af49a73f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_133e9574-d94f-4a53-a827-afc4af49a73f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_2e37cd9f-4b8e-4cb6-8e4d-4eac6369043e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_133e9574-d94f-4a53-a827-afc4af49a73f" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_2e37cd9f-4b8e-4cb6-8e4d-4eac6369043e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_ed58876a-5c05-4fd4-8428-7ddd6ec684d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_2e37cd9f-4b8e-4cb6-8e4d-4eac6369043e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_ed58876a-5c05-4fd4-8428-7ddd6ec684d3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_71396050-e0c1-458c-90b4-2b99b5abe89e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_srt_ProductOrServiceAxis_71396050-e0c1-458c-90b4-2b99b5abe89e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_bb5ee318-54d6-44ea-ab1b-d45f3a463d2f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_ProductOrServiceAxis_71396050-e0c1-458c-90b4-2b99b5abe89e" xlink:to="loc_srt_ProductsAndServicesDomain_bb5ee318-54d6-44ea-ab1b-d45f3a463d2f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_AchievementOfFirstPatientDosingMilestoneMember_b5a8f791-7885-49f0-8ab7-4375bf89f720" xlink:href="plrx-20220331.xsd#plrx_AchievementOfFirstPatientDosingMilestoneMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_ProductsAndServicesDomain_bb5ee318-54d6-44ea-ab1b-d45f3a463d2f" xlink:to="loc_plrx_AchievementOfFirstPatientDosingMilestoneMember_b5a8f791-7885-49f0-8ab7-4375bf89f720" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_523afdb2-d820-4f9b-bdc4-3c227beaf0ab" xlink:to="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NumberOfIntegrinResearchTargets_21451de6-d019-400b-920e-337b48e558c0" xlink:href="plrx-20220331.xsd#plrx_NumberOfIntegrinResearchTargets"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_plrx_NumberOfIntegrinResearchTargets_21451de6-d019-400b-920e-337b48e558c0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ProceedsFromUpfrontNonRefundableLicenseFee_9ae7a576-2b17-4143-8517-469cf1fb59c9" xlink:href="plrx-20220331.xsd#plrx_ProceedsFromUpfrontNonRefundableLicenseFee"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_plrx_ProceedsFromUpfrontNonRefundableLicenseFee_9ae7a576-2b17-4143-8517-469cf1fb59c9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmount_e372be65-ef48-4b62-bc88-2a464aacb38a" xlink:href="plrx-20220331.xsd#plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmount"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmount_e372be65-ef48-4b62-bc88-2a464aacb38a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_ed80fc74-ee9e-42f1-9bf1-18fd683953c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionAmountsOfTransaction"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_us-gaap_RelatedPartyTransactionAmountsOfTransaction_ed80fc74-ee9e-42f1-9bf1-18fd683953c5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromRelatedParties_02314979-eecb-4c18-a9fb-9ca8e2a9c7c8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueFromRelatedParties"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_us-gaap_RevenueFromRelatedParties_02314979-eecb-4c18-a9fb-9ca8e2a9c7c8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmountRemaining_7e79be36-03cc-4674-b74e-48bbd68d1a5f" xlink:href="plrx-20220331.xsd#plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmountRemaining"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_360ff994-9cfe-4db0-94a3-4fe0c3a3ce54" xlink:to="loc_plrx_CollaborationAndLicenseAgreementIntegrinResearchTargetsAmountRemaining_7e79be36-03cc-4674-b74e-48bbd68d1a5f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_16af64f8-3a59-43d9-b82b-fa48c89b4876" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OrganizationConsolidationAndPresentationOfFinancialStatementsAbstract_16af64f8-3a59-43d9-b82b-fa48c89b4876" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_07bed6f4-7303-4662-9fb2-cb22f4d04b07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_07bed6f4-7303-4662-9fb2-cb22f4d04b07" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_eb491a88-4e9c-4633-bf7c-e1683a41499e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_07bed6f4-7303-4662-9fb2-cb22f4d04b07" xlink:to="loc_us-gaap_RelatedPartyDomain_eb491a88-4e9c-4633-bf7c-e1683a41499e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisMember_addae25c-6cfe-48a4-8cf6-a99ecf20fc08" xlink:href="plrx-20220331.xsd#plrx_NovartisMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyDomain_eb491a88-4e9c-4633-bf7c-e1683a41499e" xlink:to="loc_plrx_NovartisMember_addae25c-6cfe-48a4-8cf6-a99ecf20fc08" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_96ff65ff-3ecf-4ce8-b11c-743c20925adf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:to="loc_us-gaap_TypeOfArrangementAxis_96ff65ff-3ecf-4ce8-b11c-743c20925adf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d7196071-1487-4188-911a-b6b69e4e5b8c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TypeOfArrangementAxis_96ff65ff-3ecf-4ce8-b11c-743c20925adf" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d7196071-1487-4188-911a-b6b69e4e5b8c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NovartisAgreementRDForIntegrinResearchTargetsMember_2a963123-6ef4-42a4-a5a1-f53f36e769b7" xlink:href="plrx-20220331.xsd#plrx_NovartisAgreementRDForIntegrinResearchTargetsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_d7196071-1487-4188-911a-b6b69e4e5b8c" xlink:to="loc_plrx_NovartisAgreementRDForIntegrinResearchTargetsMember_2a963123-6ef4-42a4-a5a1-f53f36e769b7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_e9803578-109f-4eeb-8dc1-af2e8ba007c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_e9803578-109f-4eeb-8dc1-af2e8ba007c2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4009c2b8-ab51-4ab0-86bd-25b7c88e3de8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_1076fda4-3727-4523-8fb3-18c11ca47fa5" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4009c2b8-ab51-4ab0-86bd-25b7c88e3de8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_e5d75e8f-ddcb-4fb9-b09d-f7ab23b231e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4009c2b8-ab51-4ab0-86bd-25b7c88e3de8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_e5d75e8f-ddcb-4fb9-b09d-f7ab23b231e3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5c251185-1857-4c60-9f81-5e77b9f07ede" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_4009c2b8-ab51-4ab0-86bd-25b7c88e3de8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_5c251185-1857-4c60-9f81-5e77b9f07ede" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails_1" xlink:type="simple" xlink:href="plrx-20220331.xsd#NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails_1"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NovartisCollaborationandLicenseAgreementtheNovartisAgreementPerformanceObligationDetails_1" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreement" xlink:type="simple" xlink:href="plrx-20220331.xsd#RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreement"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LicenseAgreementsAbstract_2166d476-52ff-4752-92b8-637141ee9f13" xlink:href="plrx-20220331.xsd#plrx_LicenseAgreementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LicenseAgreementsTextBlock_740233ac-1fdd-43af-b2b6-cf5b851c633e" xlink:href="plrx-20220331.xsd#plrx_LicenseAgreementsTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsAbstract_2166d476-52ff-4752-92b8-637141ee9f13" xlink:to="loc_plrx_LicenseAgreementsTextBlock_740233ac-1fdd-43af-b2b6-cf5b851c633e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreementNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreementNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RegentoftheUniversityofCaliforniaLicenseAgreementtheUCAgreementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LicenseAgreementsAbstract_ce87176c-39bb-4f47-8412-aad379b4b751" xlink:href="plrx-20220331.xsd#plrx_LicenseAgreementsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LicenseAgreementsTable_8db5db3c-60b5-4adb-8f1f-046c9a67d4bb" xlink:href="plrx-20220331.xsd#plrx_LicenseAgreementsTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsAbstract_ce87176c-39bb-4f47-8412-aad379b4b751" xlink:to="loc_plrx_LicenseAgreementsTable_8db5db3c-60b5-4adb-8f1f-046c9a67d4bb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3d0a1a69-1f45-4c9a-a7c7-c3dea5c7fd6c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsTable_8db5db3c-60b5-4adb-8f1f-046c9a67d4bb" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3d0a1a69-1f45-4c9a-a7c7-c3dea5c7fd6c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b4705140-6e82-4d5c-9f51-9b701d4c5630" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_3d0a1a69-1f45-4c9a-a7c7-c3dea5c7fd6c" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b4705140-6e82-4d5c-9f51-9b701d4c5630" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_60826815-4254-4b65-85fe-9bc83905d372" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_b4705140-6e82-4d5c-9f51-9b701d4c5630" xlink:to="loc_us-gaap_LicensingAgreementsMember_60826815-4254-4b65-85fe-9bc83905d372" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_bb6146d2-3cb3-4782-a4d5-e4fdf806e684" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductOrServiceAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsTable_8db5db3c-60b5-4adb-8f1f-046c9a67d4bb" xlink:to="loc_srt_ProductOrServiceAxis_bb6146d2-3cb3-4782-a4d5-e4fdf806e684" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_74116e11-8d42-4c97-a394-d26f6aa490e8" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_ProductsAndServicesDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_ProductOrServiceAxis_bb6146d2-3cb3-4782-a4d5-e4fdf806e684" xlink:to="loc_srt_ProductsAndServicesDomain_74116e11-8d42-4c97-a394-d26f6aa490e8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_UCRegentsMember_bff742e8-c8f5-447c-b592-1afdaaf2c4e3" xlink:href="plrx-20220331.xsd#plrx_UCRegentsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_ProductsAndServicesDomain_74116e11-8d42-4c97-a394-d26f6aa490e8" xlink:to="loc_plrx_UCRegentsMember_bff742e8-c8f5-447c-b592-1afdaaf2c4e3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LicenseAgreementsLineItems_f0a5d5fc-476f-4a73-83d8-ed4c90108535" xlink:href="plrx-20220331.xsd#plrx_LicenseAgreementsLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsTable_8db5db3c-60b5-4adb-8f1f-046c9a67d4bb" xlink:to="loc_plrx_LicenseAgreementsLineItems_f0a5d5fc-476f-4a73-83d8-ed4c90108535" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_MilestoneAndAnnualRoyaltyPaid_e8209242-6190-41c2-b584-2e6830b9d84a" xlink:href="plrx-20220331.xsd#plrx_MilestoneAndAnnualRoyaltyPaid"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_LicenseAgreementsLineItems_f0a5d5fc-476f-4a73-83d8-ed4c90108535" xlink:to="loc_plrx_MilestoneAndAnnualRoyaltyPaid_e8209242-6190-41c2-b584-2e6830b9d84a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/AdimabDevelopmentandOptionAgreementtheAdimabAgreement" xlink:type="simple" xlink:href="plrx-20220331.xsd#AdimabDevelopmentandOptionAgreementtheAdimabAgreement"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/AdimabDevelopmentandOptionAgreementtheAdimabAgreement" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentAbstract_334a4747-3a1b-48da-8c42-1f91bde532bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchDevelopmentAndComputerSoftwareDisclosureTextBlock_e5e97132-8a48-4405-8d4c-f8604e7f2973" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchDevelopmentAndComputerSoftwareDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_334a4747-3a1b-48da-8c42-1f91bde532bd" xlink:to="loc_us-gaap_ResearchDevelopmentAndComputerSoftwareDisclosureTextBlock_e5e97132-8a48-4405-8d4c-f8604e7f2973" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/AdimabDevelopmentandOptionAgreementtheAdimabAgreementNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#AdimabDevelopmentandOptionAgreementtheAdimabAgreementNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/AdimabDevelopmentandOptionAgreementtheAdimabAgreementNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentAbstract_db0273f4-6d63-4f03-b4d4-a0c69e948438" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable_9249f36c-3c9c-4066-8f8a-7fef19597ba1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ResearchAndDevelopmentAbstract_db0273f4-6d63-4f03-b4d4-a0c69e948438" xlink:to="loc_us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable_9249f36c-3c9c-4066-8f8a-7fef19597ba1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_579d08ff-e21d-4d45-8b33-495bf74035e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable_9249f36c-3c9c-4066-8f8a-7fef19597ba1" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_579d08ff-e21d-4d45-8b33-495bf74035e1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_e5a4205a-b42d-4e81-97a7-7889592b59bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_579d08ff-e21d-4d45-8b33-495bf74035e1" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_e5a4205a-b42d-4e81-97a7-7889592b59bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_AdimabAgreementMember_5f534ccb-a8c4-4c82-b61b-023508753cd6" xlink:href="plrx-20220331.xsd#plrx_AdimabAgreementMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_e5a4205a-b42d-4e81-97a7-7889592b59bf" xlink:to="loc_plrx_AdimabAgreementMember_5f534ccb-a8c4-4c82-b61b-023508753cd6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems_ee5ecca3-e0c3-49b7-8b08-db1856de2671" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfResearchAndDevelopmentArrangementContractToPerformForOthersTable_9249f36c-3c9c-4066-8f8a-7fef19597ba1" xlink:to="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems_ee5ecca3-e0c3-49b7-8b08-db1856de2671" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_7e27d9b4-7d51-423d-8121-a4a9b289e7c3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersLineItems_ee5ecca3-e0c3-49b7-8b08-db1856de2671" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_7e27d9b4-7d51-423d-8121-a4a9b289e7c3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RedeemableConvertiblePreferredStock" xlink:type="simple" xlink:href="plrx-20220331.xsd#RedeemableConvertiblePreferredStock"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RedeemableConvertiblePreferredStock" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityDisclosureAbstract_b3baede6-11cd-49a9-b054-96f36d29b4dd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RedeemableConvertiblePreferredStockTextBlock_4ae71d7d-ed9f-4a09-91d1-7a0424feec31" xlink:href="plrx-20220331.xsd#plrx_RedeemableConvertiblePreferredStockTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityDisclosureAbstract_b3baede6-11cd-49a9-b054-96f36d29b4dd" xlink:to="loc_plrx_RedeemableConvertiblePreferredStockTextBlock_4ae71d7d-ed9f-4a09-91d1-7a0424feec31" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RedeemableConvertiblePreferredStockAdditionalInformationDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#RedeemableConvertiblePreferredStockAdditionalInformationDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RedeemableConvertiblePreferredStockAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityDisclosureAbstract_2b39ce00-9a9a-4d06-932b-2de13f4aee46" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityByClassOfStockTable_b2f6c3e7-a3ac-4d14-912e-a047aad8024a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityByClassOfStockTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityDisclosureAbstract_2b39ce00-9a9a-4d06-932b-2de13f4aee46" xlink:to="loc_us-gaap_TemporaryEquityByClassOfStockTable_b2f6c3e7-a3ac-4d14-912e-a047aad8024a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_e7e7285d-b524-4fe5-8309-d79da49eb6b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_b2f6c3e7-a3ac-4d14-912e-a047aad8024a" xlink:to="loc_us-gaap_StatementClassOfStockAxis_e7e7285d-b524-4fe5-8309-d79da49eb6b0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_a30d1a8c-15bd-4c47-9faf-37a510393bda" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_StatementClassOfStockAxis_e7e7285d-b524-4fe5-8309-d79da49eb6b0" xlink:to="loc_us-gaap_ClassOfStockDomain_a30d1a8c-15bd-4c47-9faf-37a510393bda" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RedeemablePreferredStockMember_cc564e61-f909-4769-a130-fa0894d07e8e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RedeemablePreferredStockMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ClassOfStockDomain_a30d1a8c-15bd-4c47-9faf-37a510393bda" xlink:to="loc_us-gaap_RedeemablePreferredStockMember_cc564e61-f909-4769-a130-fa0894d07e8e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityLineItems_c4c17337-05c7-4414-a6b4-bb1b807399ce" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_TemporaryEquityLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityByClassOfStockTable_b2f6c3e7-a3ac-4d14-912e-a047aad8024a" xlink:to="loc_us-gaap_TemporaryEquityLineItems_c4c17337-05c7-4414-a6b4-bb1b807399ce" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NumberOfClassesOfStockAuthorized_cddc9963-c961-4ffb-8aa8-eff171a6a07d" xlink:href="plrx-20220331.xsd#plrx_NumberOfClassesOfStockAuthorized"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityLineItems_c4c17337-05c7-4414-a6b4-bb1b807399ce" xlink:to="loc_plrx_NumberOfClassesOfStockAuthorized_cddc9963-c961-4ffb-8aa8-eff171a6a07d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_6a0f38ab-a1dd-4708-8cc1-6a21361f3732" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityLineItems_c4c17337-05c7-4414-a6b4-bb1b807399ce" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_6a0f38ab-a1dd-4708-8cc1-6a21361f3732" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_36baed9f-209f-40fe-934b-0e6ee27b78d1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_TemporaryEquityLineItems_c4c17337-05c7-4414-a6b4-bb1b807399ce" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_36baed9f-209f-40fe-934b-0e6ee27b78d1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommonStock" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommonStock"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommonStock" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract_1a3e1467-a181-4bcd-bad4-fa62220a7ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_f1a5339c-5efe-4802-bc55-b0949a4cdcb0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_1a3e1467-a181-4bcd-bad4-fa62220a7ec9" xlink:to="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_f1a5339c-5efe-4802-bc55-b0949a4cdcb0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommonStockTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommonStockTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommonStockTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract_1bb7a617-542d-4f7b-8e8f-e18d6fc91319" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ScheduleOfCommonStockReservedForFutureIssuanceTableTableTextBlock_dd4564eb-161d-4d3b-977a-5bb84b080301" xlink:href="plrx-20220331.xsd#plrx_ScheduleOfCommonStockReservedForFutureIssuanceTableTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_1bb7a617-542d-4f7b-8e8f-e18d6fc91319" xlink:to="loc_plrx_ScheduleOfCommonStockReservedForFutureIssuanceTableTableTextBlock_dd4564eb-161d-4d3b-977a-5bb84b080301" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommonStockNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommonStockNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommonStockNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_42bc1756-3e57-4e81-80c4-11177bce615e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_42bc1756-3e57-4e81-80c4-11177bce615e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_1831998e-a782-4b9f-a289-382621681972" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_1831998e-a782-4b9f-a289-382621681972" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockVotingRights_889884e9-ae9b-44e0-ac34-942decf9294c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockVotingRights"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:to="loc_us-gaap_CommonStockVotingRights_889884e9-ae9b-44e0-ac34-942decf9294c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_ce9afd3b-3e5e-4300-8269-098bda859908" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_ce9afd3b-3e5e-4300-8269-098bda859908" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareCashPaid_6219c354-0e72-43d0-94ee-ee91ce76e88b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockDividendsPerShareCashPaid"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_585ee085-ede9-41ad-8f9e-8f215fbde50a" xlink:to="loc_us-gaap_CommonStockDividendsPerShareCashPaid_6219c354-0e72-43d0-94ee-ee91ce76e88b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommonStockScheduleofSharesReservedforFutureIssuanceDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommonStockScheduleofSharesReservedforFutureIssuanceDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommonStockScheduleofSharesReservedforFutureIssuanceDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityAbstract_60e642b3-8304-428d-a569-682363127ecd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EquityAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_111901ed-0e87-4a7e-bb6d-2cc92a959cb0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EquityAbstract_60e642b3-8304-428d-a569-682363127ecd" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_111901ed-0e87-4a7e-bb6d-2cc92a959cb0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_b55bc06e-af38-4b19-9d6f-3f2817a95729" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_111901ed-0e87-4a7e-bb6d-2cc92a959cb0" xlink:to="loc_us-gaap_AwardTypeAxis_b55bc06e-af38-4b19-9d6f-3f2817a95729" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1f60392b-f049-42e6-936c-f0fb4aa9d0a4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_b55bc06e-af38-4b19-9d6f-3f2817a95729" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1f60392b-f049-42e6-936c-f0fb4aa9d0a4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_3c0a86e5-7cae-4669-9813-85570269e6ca" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1f60392b-f049-42e6-936c-f0fb4aa9d0a4" xlink:to="loc_us-gaap_EmployeeStockOptionMember_3c0a86e5-7cae-4669-9813-85570269e6ca" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_64c16a21-5abe-48d1-bbe5-d8334f722a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_111901ed-0e87-4a7e-bb6d-2cc92a959cb0" xlink:to="loc_us-gaap_PlanNameAxis_64c16a21-5abe-48d1-bbe5-d8334f722a6f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_244b6823-0a24-4f08-912e-f1c20477bd47" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_64c16a21-5abe-48d1-bbe5-d8334f722a6f" xlink:to="loc_us-gaap_PlanNameDomain_244b6823-0a24-4f08-912e-f1c20477bd47" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandTwentyEquityIncentivePlanMember_052956be-428c-480a-b92a-a651109434ce" xlink:href="plrx-20220331.xsd#plrx_TwoThousandTwentyEquityIncentivePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_244b6823-0a24-4f08-912e-f1c20477bd47" xlink:to="loc_plrx_TwoThousandTwentyEquityIncentivePlanMember_052956be-428c-480a-b92a-a651109434ce" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_07c89e46-6bfb-4164-808e-584e256b10fd" xlink:href="plrx-20220331.xsd#plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_244b6823-0a24-4f08-912e-f1c20477bd47" xlink:to="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_07c89e46-6bfb-4164-808e-584e256b10fd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_64e4775f-b89a-4a2b-8d97-9b1efc9a411d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_111901ed-0e87-4a7e-bb6d-2cc92a959cb0" xlink:to="loc_us-gaap_ClassOfStockLineItems_64e4775f-b89a-4a2b-8d97-9b1efc9a411d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_57f46e17-1c84-4c9c-9cf1-ca2c0fceefd5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ClassOfStockLineItems_64e4775f-b89a-4a2b-8d97-9b1efc9a411d" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_57f46e17-1c84-4c9c-9cf1-ca2c0fceefd5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensation"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_0001cc6b-c9ee-4053-ab3f-53009994929e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_e70658d2-2fb9-462c-947e-10bbd0edb69d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_0001cc6b-c9ee-4053-ab3f-53009994929e" xlink:to="loc_us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_e70658d2-2fb9-462c-947e-10bbd0edb69d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_cf389203-9c47-4088-a8a0-26e04b944587" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationRestrictedStockUnitsAwardActivityTableTextBlock_cf389203-9c47-4088-a8a0-26e04b944587" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_4d212a07-6d10-4c3e-a5dc-74111fdbdd24" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:to="loc_us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock_4d212a07-6d10-4c3e-a5dc-74111fdbdd24" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_40ac2713-bafe-4ebe-914c-f7f74526e954" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationStockOptionsActivityTableTextBlock_40ac2713-bafe-4ebe-914c-f7f74526e954" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_636e389b-41e1-4a4c-8b93-d7950733c2bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:to="loc_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_636e389b-41e1-4a4c-8b93-d7950733c2bc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock_857b4c06-16b9-4031-85e9-783e2ca6e8a3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_97cb79ab-1b29-4265-8fcf-f81ee7680d7b" xlink:to="loc_us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock_857b4c06-16b9-4031-85e9-783e2ca6e8a3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationEquityIncentivePlanNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationEquityIncentivePlanNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationEquityIncentivePlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_e04b8041-d2c7-4e21-942e-d51f8e01231d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6ece6e6-2e7f-4872-93da-8d93955f7bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_e04b8041-d2c7-4e21-942e-d51f8e01231d" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6ece6e6-2e7f-4872-93da-8d93955f7bf1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_3a124992-d3df-4cf8-88c6-94c4b30af34e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6ece6e6-2e7f-4872-93da-8d93955f7bf1" xlink:to="loc_srt_RangeAxis_3a124992-d3df-4cf8-88c6-94c4b30af34e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_cba97f03-86ee-4b05-bacd-d7243ba52a77" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeAxis_3a124992-d3df-4cf8-88c6-94c4b30af34e" xlink:to="loc_srt_RangeMember_cba97f03-86ee-4b05-bacd-d7243ba52a77" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_40d3a51b-9d99-499d-a4c1-1c7b6d9b9de7" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_cba97f03-86ee-4b05-bacd-d7243ba52a77" xlink:to="loc_srt_MaximumMember_40d3a51b-9d99-499d-a4c1-1c7b6d9b9de7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_9cd8de39-7e1d-45f4-9285-13a6ed29d260" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6ece6e6-2e7f-4872-93da-8d93955f7bf1" xlink:to="loc_us-gaap_PlanNameAxis_9cd8de39-7e1d-45f4-9285-13a6ed29d260" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_77200a5c-4861-4dd7-98a7-9a314a86a197" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_9cd8de39-7e1d-45f4-9285-13a6ed29d260" xlink:to="loc_us-gaap_PlanNameDomain_77200a5c-4861-4dd7-98a7-9a314a86a197" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandFifteenEquityIncentivePlanMember_5731a2ff-674b-4237-8e7c-ef1b07cc4279" xlink:href="plrx-20220331.xsd#plrx_TwoThousandFifteenEquityIncentivePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_77200a5c-4861-4dd7-98a7-9a314a86a197" xlink:to="loc_plrx_TwoThousandFifteenEquityIncentivePlanMember_5731a2ff-674b-4237-8e7c-ef1b07cc4279" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember_66391c72-95a2-45b0-b4bc-8ecb35f6ba6c" xlink:href="plrx-20220331.xsd#plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_77200a5c-4861-4dd7-98a7-9a314a86a197" xlink:to="loc_plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember_66391c72-95a2-45b0-b4bc-8ecb35f6ba6c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_e6ece6e6-2e7f-4872-93da-8d93955f7bf1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_67b28082-410e-4336-9f5e-17a7010cb4e3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_67b28082-410e-4336-9f5e-17a7010cb4e3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_109c56c2-fead-429f-aa30-22990a87912d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_109c56c2-fead-429f-aa30-22990a87912d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_f3ad23db-4d9a-436f-97d1-af090d6bcd1b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_f3ad23db-4d9a-436f-97d1-af090d6bcd1b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_718401d7-b63a-4f69-af46-1df65983f28a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_718401d7-b63a-4f69-af46-1df65983f28a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfEstimatedFairValueOfShares_07391b35-3523-45cf-bedb-99bfe00e074a" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfEstimatedFairValueOfShares"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentOfEstimatedFairValueOfShares_07391b35-3523-45cf-bedb-99bfe00e074a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationOptionsUnderPlanMayBeGrantedForPeriods_2b3cdd54-4b0a-444f-9fce-b3000be510af" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationOptionsUnderPlanMayBeGrantedForPeriods"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_plrx_ShareBasedCompensationOptionsUnderPlanMayBeGrantedForPeriods_2b3cdd54-4b0a-444f-9fce-b3000be510af" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceWithPurchasePriceOfCommonStockPercentageOfEstimatedGrantDateFairValueForShareholders_32452119-e00a-4763-9d34-f1aa034433d7" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceWithPurchasePriceOfCommonStockPercentageOfEstimatedGrantDateFairValueForShareholders"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceWithPurchasePriceOfCommonStockPercentageOfEstimatedGrantDateFairValueForShareholders_32452119-e00a-4763-9d34-f1aa034433d7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_f79c3c8d-d0cb-43ed-92df-d3a79390b3cf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_e57f58fe-ba2a-4fbe-b08e-47bb1bf1f870" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_f79c3c8d-d0cb-43ed-92df-d3a79390b3cf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationRestrictedCommonStockAwardsNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationRestrictedCommonStockAwardsNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationRestrictedCommonStockAwardsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_b3a32825-7346-4034-9209-20a62ec538db" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_b3a32825-7346-4034-9209-20a62ec538db" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_4f1638f5-aeb7-4045-b67a-a7846573c16d" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:to="loc_srt_RangeAxis_4f1638f5-aeb7-4045-b67a-a7846573c16d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a8975f4f-2052-40c9-ad45-d6c6c84fa97b" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeAxis_4f1638f5-aeb7-4045-b67a-a7846573c16d" xlink:to="loc_srt_RangeMember_a8975f4f-2052-40c9-ad45-d6c6c84fa97b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_567119dc-1bd7-47ba-8562-8aba9c441971" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_a8975f4f-2052-40c9-ad45-d6c6c84fa97b" xlink:to="loc_srt_MinimumMember_567119dc-1bd7-47ba-8562-8aba9c441971" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e05ee6a3-7e7f-4937-bda9-8d204fa6cd27" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_a8975f4f-2052-40c9-ad45-d6c6c84fa97b" xlink:to="loc_srt_MaximumMember_e05ee6a3-7e7f-4937-bda9-8d204fa6cd27" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_d2410b50-a1d4-401e-b6a9-69d8b4ee65bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:to="loc_us-gaap_PlanNameAxis_d2410b50-a1d4-401e-b6a9-69d8b4ee65bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_efb40434-5674-4832-a831-6b984aff409f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_d2410b50-a1d4-401e-b6a9-69d8b4ee65bf" xlink:to="loc_us-gaap_PlanNameDomain_efb40434-5674-4832-a831-6b984aff409f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RestrictedCommonStockAwardsMember_96e6bb8b-6c1d-4bd7-bf21-4f9242b1cd35" xlink:href="plrx-20220331.xsd#plrx_RestrictedCommonStockAwardsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_efb40434-5674-4832-a831-6b984aff409f" xlink:to="loc_plrx_RestrictedCommonStockAwardsMember_96e6bb8b-6c1d-4bd7-bf21-4f9242b1cd35" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_9f361e5c-0dce-4176-ac29-ef06e095dc8a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_9f361e5c-0dce-4176-ac29-ef06e095dc8a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_bcda10d8-0228-42bf-b734-666ea1f5c854" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_9f361e5c-0dce-4176-ac29-ef06e095dc8a" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_bcda10d8-0228-42bf-b734-666ea1f5c854" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_AccruedExpensesAndOtherLiabilitiesMember_f05893f2-7108-4e6d-b816-4cbc221e1332" xlink:href="plrx-20220331.xsd#plrx_AccruedExpensesAndOtherLiabilitiesMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_bcda10d8-0228-42bf-b734-666ea1f5c854" xlink:to="loc_plrx_AccruedExpensesAndOtherLiabilitiesMember_f05893f2-7108-4e6d-b816-4cbc221e1332" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_1a22fb52-c991-43b7-b649-6d47c49011f2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_3c04a68a-e0a1-4e7c-be25-d9e53564254d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_3c04a68a-e0a1-4e7c-be25-d9e53564254d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_050dfea4-82ea-4f26-997d-a13e345c8da9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:to="loc_us-gaap_DeferredCompensationShareBasedArrangementsLiabilityCurrent_050dfea4-82ea-4f26-997d-a13e345c8da9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5bc7b68e-3359-483f-8dfd-f6e7b9361541" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5bc7b68e-3359-483f-8dfd-f6e7b9361541" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_3344e495-a496-4971-90e8-50bf23901869" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested_3344e495-a496-4971-90e8-50bf23901869" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_ce288e90-fa46-4fbe-bb55-2765bdad9ebe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_828f305f-cbe9-4628-b161-6962bf244846" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_ce288e90-fa46-4fbe-bb55-2765bdad9ebe" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofRestrictedStockActivityDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationSummaryofRestrictedStockActivityDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofRestrictedStockActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_d090f11e-2746-4eac-99fa-b42abee0e07a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_afc99588-b593-46a5-a100-4b1884e59dcc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_d090f11e-2746-4eac-99fa-b42abee0e07a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_afc99588-b593-46a5-a100-4b1884e59dcc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_d17d0434-6ec0-4904-9c2d-882ffabc2d71" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_afc99588-b593-46a5-a100-4b1884e59dcc" xlink:to="loc_us-gaap_PlanNameAxis_d17d0434-6ec0-4904-9c2d-882ffabc2d71" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_54f14cd6-cdb5-4be1-beec-2840790d0a3c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_d17d0434-6ec0-4904-9c2d-882ffabc2d71" xlink:to="loc_us-gaap_PlanNameDomain_54f14cd6-cdb5-4be1-beec-2840790d0a3c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RestrictedCommonStockAwardsMember_1414f1f7-8656-41a0-b250-c242059b4f31" xlink:href="plrx-20220331.xsd#plrx_RestrictedCommonStockAwardsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_54f14cd6-cdb5-4be1-beec-2840790d0a3c" xlink:to="loc_plrx_RestrictedCommonStockAwardsMember_1414f1f7-8656-41a0-b250-c242059b4f31" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d2652a46-e870-41c3-8da4-6fd008c36595" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_afc99588-b593-46a5-a100-4b1884e59dcc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d2652a46-e870-41c3-8da4-6fd008c36595" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d2652a46-e870-41c3-8da4-6fd008c36595" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_519af93f-14f2-4030-bcc5-e65592560b4c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_519af93f-14f2-4030-bcc5-e65592560b4c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a46ae6d3-2368-4bd1-a26b-995ebffd3597" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_a46ae6d3-2368-4bd1-a26b-995ebffd3597" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_dd93c7e8-e201-4304-a4e9-42158a8bf11a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_dd93c7e8-e201-4304-a4e9-42158a8bf11a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesInPeriod_843fb7e3-aef7-4fe8-8eb7-425ec49861ff" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesInPeriod"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:to="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesInPeriod_843fb7e3-aef7-4fe8-8eb7-425ec49861ff" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_144e4540-4ae8-4c16-87dc-66d7ad3e6aab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_4bc385d5-69a2-49dd-a60d-5aa3ff747ca0" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_144e4540-4ae8-4c16-87dc-66d7ad3e6aab" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d2652a46-e870-41c3-8da4-6fd008c36595" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1306dc98-614a-4c12-91a1-b7161e3cfe35" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_1306dc98-614a-4c12-91a1-b7161e3cfe35" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a4bd0465-3330-45a4-b407-fd620db227bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a4bd0465-3330-45a4-b407-fd620db227bd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_0d3068d4-32d6-44ac-a1b0-e66b36151beb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_0d3068d4-32d6-44ac-a1b0-e66b36151beb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesWeightedAverageGrantDateFairValue_bb2a7741-ba13-4e3d-812c-8de48b10e307" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:to="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsRepurchasesWeightedAverageGrantDateFairValue_bb2a7741-ba13-4e3d-812c-8de48b10e307" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ff88bdc6-71b4-48e8-880d-987067a5985f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_5d02c8f1-6cd6-4d50-a603-9eeb873276fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_ff88bdc6-71b4-48e8-880d-987067a5985f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationIncentiveStockOptionsandNonqualifiedStockOptionsNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationIncentiveStockOptionsandNonqualifiedStockOptionsNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationIncentiveStockOptionsandNonqualifiedStockOptionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_53579c9e-c6e0-491e-b650-0064f52d2476" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_499038ab-4454-4ab3-b204-0cbcdda60586" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_53579c9e-c6e0-491e-b650-0064f52d2476" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_499038ab-4454-4ab3-b204-0cbcdda60586" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_77fd3e6c-de54-4efd-aeab-33406738a7c5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_499038ab-4454-4ab3-b204-0cbcdda60586" xlink:to="loc_us-gaap_AwardTypeAxis_77fd3e6c-de54-4efd-aeab-33406738a7c5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e40b5584-48b9-4c4e-9ea4-2d6b73b0d038" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_77fd3e6c-de54-4efd-aeab-33406738a7c5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e40b5584-48b9-4c4e-9ea4-2d6b73b0d038" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_ec1480c6-3f08-41a9-803d-fa68fb4158ce" xlink:href="plrx-20220331.xsd#plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_e40b5584-48b9-4c4e-9ea4-2d6b73b0d038" xlink:to="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_ec1480c6-3f08-41a9-803d-fa68fb4158ce" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_cd8f7da9-a8fc-49c8-9234-6891baddb426" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_499038ab-4454-4ab3-b204-0cbcdda60586" xlink:to="loc_us-gaap_PlanNameAxis_cd8f7da9-a8fc-49c8-9234-6891baddb426" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_dd8fa3e2-1c55-41ef-a894-a49d48bbfa99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_cd8f7da9-a8fc-49c8-9234-6891baddb426" xlink:to="loc_us-gaap_PlanNameDomain_dd8fa3e2-1c55-41ef-a894-a49d48bbfa99" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember_63a7cc2d-fd3e-43a3-87b7-978ce664d864" xlink:href="plrx-20220331.xsd#plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_dd8fa3e2-1c55-41ef-a894-a49d48bbfa99" xlink:to="loc_plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember_63a7cc2d-fd3e-43a3-87b7-978ce664d864" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember_f903873a-40f1-470b-aa56-c31e27d81987" xlink:href="plrx-20220331.xsd#plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_dd8fa3e2-1c55-41ef-a894-a49d48bbfa99" xlink:to="loc_plrx_TwoThousandAndTwentyStockOptionsAndIncentivePlanMember_f903873a-40f1-470b-aa56-c31e27d81987" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_499038ab-4454-4ab3-b204-0cbcdda60586" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_1b7dcea9-3982-45c8-b960-a56393ab3f43" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_1b7dcea9-3982-45c8-b960-a56393ab3f43" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_28ee52cd-7706-439f-8d88-cda35addd912" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_28ee52cd-7706-439f-8d88-cda35addd912" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_af7fe8b5-9228-4bfe-9ddd-d08350380abb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_af7fe8b5-9228-4bfe-9ddd-d08350380abb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_72afa584-cdf9-42f7-b0c9-cb01275a9010" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_64871537-6964-491e-a1ce-3cf97dc948bd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_72afa584-cdf9-42f7-b0c9-cb01275a9010" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpenseforStockOptionAwardsDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpenseforStockOptionAwardsDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpenseforStockOptionAwardsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_30308cd2-0b3a-4b9d-b76e-d0187e3495cd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f980e931-78b6-4a82-a84f-dcd1f7e3b027" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_30308cd2-0b3a-4b9d-b76e-d0187e3495cd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f980e931-78b6-4a82-a84f-dcd1f7e3b027" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_02043391-ba06-4140-b6c2-0500747f8293" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f980e931-78b6-4a82-a84f-dcd1f7e3b027" xlink:to="loc_us-gaap_AwardTypeAxis_02043391-ba06-4140-b6c2-0500747f8293" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bcd3d851-a622-4e37-aaf1-5a343f57d0aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_02043391-ba06-4140-b6c2-0500747f8293" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bcd3d851-a622-4e37-aaf1-5a343f57d0aa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_8a60135e-b673-4751-a992-676c2dcf77e9" xlink:href="plrx-20220331.xsd#plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_bcd3d851-a622-4e37-aaf1-5a343f57d0aa" xlink:to="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_8a60135e-b673-4751-a992-676c2dcf77e9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_d07d52cd-f7a3-4ea1-b85b-a3713d576d30" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f980e931-78b6-4a82-a84f-dcd1f7e3b027" xlink:to="loc_srt_RangeAxis_d07d52cd-f7a3-4ea1-b85b-a3713d576d30" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5e7b7be1-7a1d-4a05-acf4-8cf1545e795f" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeAxis_d07d52cd-f7a3-4ea1-b85b-a3713d576d30" xlink:to="loc_srt_RangeMember_5e7b7be1-7a1d-4a05-acf4-8cf1545e795f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_22243fe9-6012-427e-ad02-d70b6dab64b1" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_5e7b7be1-7a1d-4a05-acf4-8cf1545e795f" xlink:to="loc_srt_MinimumMember_22243fe9-6012-427e-ad02-d70b6dab64b1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_cc69f510-6c21-47ac-8b11-02eac1fafe01" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_5e7b7be1-7a1d-4a05-acf4-8cf1545e795f" xlink:to="loc_srt_MaximumMember_cc69f510-6c21-47ac-8b11-02eac1fafe01" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_f980e931-78b6-4a82-a84f-dcd1f7e3b027" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_77639ca6-7d1a-4021-96e2-fd17b9404073" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_77639ca6-7d1a-4021-96e2-fd17b9404073" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_9194532c-6f9a-483c-98f1-462c9f74bf4b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_9194532c-6f9a-483c-98f1-462c9f74bf4b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_3f966205-1313-4728-b27c-9bc031456679" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_3f966205-1313-4728-b27c-9bc031456679" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_699512d2-a320-4283-8a25-fb4195c2a49e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_699512d2-a320-4283-8a25-fb4195c2a49e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_ff567f73-b074-486c-92d2-0c4696551196" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_ff567f73-b074-486c-92d2-0c4696551196" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_920d87c5-5734-4582-a960-a861cb82f49d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_920d87c5-5734-4582-a960-a861cb82f49d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_UnderlyingCommonStockFairValue_de333bc5-1421-4012-9729-7ce4d7d999d2" xlink:href="plrx-20220331.xsd#plrx_UnderlyingCommonStockFairValue"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_a46c3e73-33f5-4478-9231-8cc3fc7ad95d" xlink:to="loc_plrx_UnderlyingCommonStockFairValue_de333bc5-1421-4012-9729-7ce4d7d999d2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofOptionActivityUnderthe2015Planand2020PlanDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationSummaryofOptionActivityUnderthe2015Planand2020PlanDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofOptionActivityUnderthe2015Planand2020PlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_f1bdc3eb-8319-40d4-a62a-317fd318a3bd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_28fe2e3e-f466-459d-a73f-063bcd8c99de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_f1bdc3eb-8319-40d4-a62a-317fd318a3bd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_28fe2e3e-f466-459d-a73f-063bcd8c99de" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_6b99afb1-d876-4f63-b287-4cdab107f35c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_28fe2e3e-f466-459d-a73f-063bcd8c99de" xlink:to="loc_us-gaap_PlanNameAxis_6b99afb1-d876-4f63-b287-4cdab107f35c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_8ba1619b-08ed-4b68-b5fc-4b21fd849ffa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_PlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameAxis_6b99afb1-d876-4f63-b287-4cdab107f35c" xlink:to="loc_us-gaap_PlanNameDomain_8ba1619b-08ed-4b68-b5fc-4b21fd849ffa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember_d5931a2b-3447-40a1-bb1c-a2882bc95258" xlink:href="plrx-20220331.xsd#plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_PlanNameDomain_8ba1619b-08ed-4b68-b5fc-4b21fd849ffa" xlink:to="loc_plrx_TwoThousandFifteenAndTwoThousandTwentyEquityIncentivePlanMember_d5931a2b-3447-40a1-bb1c-a2882bc95258" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_601399a6-0ca9-42c8-9763-45e6474960fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_28fe2e3e-f466-459d-a73f-063bcd8c99de" xlink:to="loc_us-gaap_AwardTypeAxis_601399a6-0ca9-42c8-9763-45e6474960fc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93c37ac1-ad0f-48e4-82f3-1fe7db76e347" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_601399a6-0ca9-42c8-9763-45e6474960fc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93c37ac1-ad0f-48e4-82f3-1fe7db76e347" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_ba833a6d-fb87-4352-97b2-fb0332905841" xlink:href="plrx-20220331.xsd#plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_93c37ac1-ad0f-48e4-82f3-1fe7db76e347" xlink:to="loc_plrx_IncentiveStockOptionsAndNonqualifiedStockOptionsMember_ba833a6d-fb87-4352-97b2-fb0332905841" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_28fe2e3e-f466-459d-a73f-063bcd8c99de" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_382443a0-ae6a-42a5-89ac-e69c673155bf" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_382443a0-ae6a-42a5-89ac-e69c673155bf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_95430c7d-1eef-4b5f-9494-b74bef7f46b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_95430c7d-1eef-4b5f-9494-b74bef7f46b0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a8ede7be-fab1-4cc9-bbf7-13c74a1d7234" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a8ede7be-fab1-4cc9-bbf7-13c74a1d7234" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_eab84c08-8d1c-44f6-99d5-b273bed5769d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_eab84c08-8d1c-44f6-99d5-b273bed5769d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2009/role/negatedLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_7c4c8376-84f9-49d9-ad42-774a97f32472" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_7c4c8376-84f9-49d9-ad42-774a97f32472" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2ff27cd7-bd62-4b09-8d08-75f13647a3f5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_2ff27cd7-bd62-4b09-8d08-75f13647a3f5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_999ac542-cc1b-48d9-b97d-4237f00466ab" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_833bb795-74f5-414c-93de-5591e95d9db7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_999ac542-cc1b-48d9-b97d-4237f00466ab" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_62877f90-b170-4ee7-8c46-2076e96aedcb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_62877f90-b170-4ee7-8c46-2076e96aedcb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodStartLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_2fa9d18a-93d2-4939-b90a-2bdfc7ac7ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_2fa9d18a-93d2-4939-b90a-2bdfc7ac7ba5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_2733be5b-4dd7-4438-a2bc-bce32110f11e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_2733be5b-4dd7-4438-a2bc-bce32110f11e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_8dc2e97f-9348-43ad-8ec1-4fcbfd8c5ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_8dc2e97f-9348-43ad-8ec1-4fcbfd8c5ba0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_35f488d2-0b37-4bc9-866e-6614f9914f16" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_db45bd3b-cbbc-451e-8e14-1430ce35eba8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_35f488d2-0b37-4bc9-866e-6614f9914f16" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/periodEndLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_a87f5948-2c4a-4784-8981-5889efff58ba" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_a87f5948-2c4a-4784-8981-5889efff58ba" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_5ddc5396-476c-4814-9b2d-da1dbc44fbb5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_5ddc5396-476c-4814-9b2d-da1dbc44fbb5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_896c3d95-5ecd-43e3-916d-7aa4769a331a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_896c3d95-5ecd-43e3-916d-7aa4769a331a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_d55ca478-aafb-4f16-bcb9-b577525226b3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_d55ca478-aafb-4f16-bcb9-b577525226b3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_f25ed2d0-6236-4ae1-a087-a55b86bf67ea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_f25ed2d0-6236-4ae1-a087-a55b86bf67ea" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_1add205e-7986-450e-a44f-477ccd99bbf9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_1add205e-7986-450e-a44f-477ccd99bbf9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_ac94bc61-774d-4c15-8510-1436b1ac5890" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_ac94bc61-774d-4c15-8510-1436b1ac5890" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_3d865ff8-a373-4f9a-ac7f-53374b06c9fc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_f4a52a4e-91b5-4805-a36f-7d3176d1b8bc" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_3d865ff8-a373-4f9a-ac7f-53374b06c9fc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationSummaryofStockbasedCompensationExpenseDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationSummaryofStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_29cc04c9-8141-45b3-a0e2-7572bc28c285" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8338b39e-baa3-4525-85a1-25d5a47defc8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_29cc04c9-8141-45b3-a0e2-7572bc28c285" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8338b39e-baa3-4525-85a1-25d5a47defc8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_5fb9c35e-8eb9-41a6-987c-da6e17cd1ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8338b39e-baa3-4525-85a1-25d5a47defc8" xlink:to="loc_us-gaap_AwardTypeAxis_5fb9c35e-8eb9-41a6-987c-da6e17cd1ca6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a0bac6f6-4dcf-40e3-a841-4a234f9a8fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_5fb9c35e-8eb9-41a6-987c-da6e17cd1ca6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a0bac6f6-4dcf-40e3-a841-4a234f9a8fdd" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RestrictedCommonStockAwardsMember_12037f02-bf54-4a9d-a480-0b3e67c1185b" xlink:href="plrx-20220331.xsd#plrx_RestrictedCommonStockAwardsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a0bac6f6-4dcf-40e3-a841-4a234f9a8fdd" xlink:to="loc_plrx_RestrictedCommonStockAwardsMember_12037f02-bf54-4a9d-a480-0b3e67c1185b" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_EmployeeStockOptionAndPurchasePlanMember_a76d678a-d533-454e-88f3-7df22c20347e" xlink:href="plrx-20220331.xsd#plrx_EmployeeStockOptionAndPurchasePlanMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_a0bac6f6-4dcf-40e3-a841-4a234f9a8fdd" xlink:to="loc_plrx_EmployeeStockOptionAndPurchasePlanMember_a76d678a-d533-454e-88f3-7df22c20347e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_05be3ae2-e681-4b9c-bf76-6562d4b5e4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8338b39e-baa3-4525-85a1-25d5a47defc8" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_05be3ae2-e681-4b9c-bf76-6562d4b5e4fe" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_107effa5-03d1-49b4-8c65-ce2d7d462224" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_05be3ae2-e681-4b9c-bf76-6562d4b5e4fe" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_107effa5-03d1-49b4-8c65-ce2d7d462224" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5dbb6158-96ba-425c-ac48-6663c10b436f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_107effa5-03d1-49b4-8c65-ce2d7d462224" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_5dbb6158-96ba-425c-ac48-6663c10b436f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpenseMember_a17977d0-8be1-4f11-b9f5-5eb2d9fdc5de" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_GeneralAndAdministrativeExpenseMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_107effa5-03d1-49b4-8c65-ce2d7d462224" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpenseMember_a17977d0-8be1-4f11-b9f5-5eb2d9fdc5de" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bd9ece78-88bc-44a2-b149-52622b30490d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_8338b39e-baa3-4525-85a1-25d5a47defc8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bd9ece78-88bc-44a2-b149-52622b30490d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_6af69cb7-1c36-4eea-8c16-b5751417ec7a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_bd9ece78-88bc-44a2-b149-52622b30490d" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_6af69cb7-1c36-4eea-8c16-b5751417ec7a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationStockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensationStockBasedCompensationNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensationStockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_945bd3af-3abe-4c47-92e7-62f80aa55ee1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_759a5ee2-a747-4ce2-890d-eb22fe7bd508" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_945bd3af-3abe-4c47-92e7-62f80aa55ee1" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_759a5ee2-a747-4ce2-890d-eb22fe7bd508" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_66ab21c3-9705-4697-b119-9d6bfc0b2e45" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_759a5ee2-a747-4ce2-890d-eb22fe7bd508" xlink:to="loc_us-gaap_AwardTypeAxis_66ab21c3-9705-4697-b119-9d6bfc0b2e45" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c1da06e6-b1a9-46a5-8e01-28290908c637" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_66ab21c3-9705-4697-b119-9d6bfc0b2e45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c1da06e6-b1a9-46a5-8e01-28290908c637" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RestrictedStockAwardsMember_d1d3f178-7487-4b5b-890f-4f9a3aad7f8a" xlink:href="plrx-20220331.xsd#plrx_RestrictedStockAwardsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c1da06e6-b1a9-46a5-8e01-28290908c637" xlink:to="loc_plrx_RestrictedStockAwardsMember_d1d3f178-7487-4b5b-890f-4f9a3aad7f8a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_3d1376d5-b9e6-43f2-bcec-cfad2cc779e0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c1da06e6-b1a9-46a5-8e01-28290908c637" xlink:to="loc_us-gaap_EmployeeStockOptionMember_3d1376d5-b9e6-43f2-bcec-cfad2cc779e0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4e79d88e-be9c-4012-b8d5-9b2c4b27b1bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_759a5ee2-a747-4ce2-890d-eb22fe7bd508" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4e79d88e-be9c-4012-b8d5-9b2c4b27b1bc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_84367e64-e4e7-4d78-bb33-0d40a6abd7c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4e79d88e-be9c-4012-b8d5-9b2c4b27b1bc" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_84367e64-e4e7-4d78-bb33-0d40a6abd7c4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_7d2c778c-7048-43e8-b007-e5808bc6d579" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4e79d88e-be9c-4012-b8d5-9b2c4b27b1bc" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_7d2c778c-7048-43e8-b007-e5808bc6d579" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_61d0d28f-6986-4967-8719-5e8cefe0feaa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_4e79d88e-be9c-4012-b8d5-9b2c4b27b1bc" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_61d0d28f-6986-4967-8719-5e8cefe0feaa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_1cc2d1b9-b34b-4061-a29f-46d3457d2603" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7e5ab2f2-299a-4a82-a047-6b74fa830d2e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_1cc2d1b9-b34b-4061-a29f-46d3457d2603" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7e5ab2f2-299a-4a82-a047-6b74fa830d2e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_3b60221b-0928-4953-9e5d-05a2511bc39f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7e5ab2f2-299a-4a82-a047-6b74fa830d2e" xlink:to="loc_us-gaap_AwardTypeAxis_3b60221b-0928-4953-9e5d-05a2511bc39f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_743ab09d-924f-4b3b-8e05-52b5dbfe46c9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_3b60221b-0928-4953-9e5d-05a2511bc39f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_743ab09d-924f-4b3b-8e05-52b5dbfe46c9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_aca6e06f-0564-47fe-ac71-a6ffcd2ecd2e" xlink:href="plrx-20220331.xsd#plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_743ab09d-924f-4b3b-8e05-52b5dbfe46c9" xlink:to="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_aca6e06f-0564-47fe-ac71-a6ffcd2ecd2e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_7e5ab2f2-299a-4a82-a047-6b74fa830d2e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_3cc0b662-5069-4f9b-98c4-712907477d6d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_3cc0b662-5069-4f9b-98c4-712907477d6d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_112f3e85-67ef-4440-99e0-5571be871e21" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfOutstandingStockMaximum_112f3e85-67ef-4440-99e0-5571be871e21" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_a6d69cb6-316c-4d35-8d9a-5624f97c969c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumEmployeeSubscriptionRate_a6d69cb6-316c-4d35-8d9a-5624f97c969c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_EmployeeStockPurchasePlanOfferingPeriod_3b8347e1-6f71-4ae1-ad65-6cb963661ba0" xlink:href="plrx-20220331.xsd#plrx_EmployeeStockPurchasePlanOfferingPeriod"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_plrx_EmployeeStockPurchasePlanOfferingPeriod_3b8347e1-6f71-4ae1-ad65-6cb963661ba0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_CommonStockFairMarketValuePercentage_1657663e-453a-4243-9141-4d6f0db7c3cc" xlink:href="plrx-20220331.xsd#plrx_CommonStockFairMarketValuePercentage"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_plrx_CommonStockFairMarketValuePercentage_1657663e-453a-4243-9141-4d6f0db7c3cc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_4c4fd144-56ca-4fc2-aadf-7f66f4d5d0ff" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_4c4fd144-56ca-4fc2-aadf-7f66f4d5d0ff" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_c594b0b4-d7c1-4bab-8127-6a96b9d06251" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_ded1148c-4166-4c64-9be7-fb921a33d246" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_c594b0b4-d7c1-4bab-8127-6a96b9d06251" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpensefor2020EmployeeStockPurchasePlanDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpensefor2020EmployeeStockPurchasePlanDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/EquityIncentivePlansandStockBasedCompensation2020EmployeeStockPurchasePlanSummaryofBlackScholesOptionPricingModeltoEstimateStockbasedCompensationExpensefor2020EmployeeStockPurchasePlanDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_019e5c49-1563-4974-a524-198e8b47162b" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4f30ffba-6a5d-42c5-a9af-82166cb7c6c2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_019e5c49-1563-4974-a524-198e8b47162b" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4f30ffba-6a5d-42c5-a9af-82166cb7c6c2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_49f70c24-d5fb-45fd-b481-58e30d029d99" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4f30ffba-6a5d-42c5-a9af-82166cb7c6c2" xlink:to="loc_us-gaap_AwardTypeAxis_49f70c24-d5fb-45fd-b481-58e30d029d99" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6fe4b6de-899a-4f14-8e1f-b95c343f0397" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_49f70c24-d5fb-45fd-b481-58e30d029d99" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6fe4b6de-899a-4f14-8e1f-b95c343f0397" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_1d6bef80-d57c-4082-b1fd-f7e420886eb1" xlink:href="plrx-20220331.xsd#plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6fe4b6de-899a-4f14-8e1f-b95c343f0397" xlink:to="loc_plrx_TwoThousandAndTwentyEmployeeStockPurchasePlanMember_1d6bef80-d57c-4082-b1fd-f7e420886eb1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4f30ffba-6a5d-42c5-a9af-82166cb7c6c2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_de69f147-04ab-49fc-823b-50ed90857c91" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_de69f147-04ab-49fc-823b-50ed90857c91" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_c46afa1e-f82a-4701-bc9e-8f044f83e200" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_c46afa1e-f82a-4701-bc9e-8f044f83e200" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_71b5e66f-ee7a-478f-b124-70f57fb3827c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_71b5e66f-ee7a-478f-b124-70f57fb3827c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_89e0e4c8-1146-443b-9d67-a975811bd34f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_d59426e9-0ad3-4ee9-9459-506089a9b5e1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_89e0e4c8-1146-443b-9d67-a975811bd34f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/IncomeTaxes" xlink:type="simple" xlink:href="plrx-20220331.xsd#IncomeTaxes"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/IncomeTaxes" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_dbea64bd-32ef-4219-9a28-2d30eda9bf56" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureTextBlock_e74111cd-f0df-465b-9e2c-5b7e62555150" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_dbea64bd-32ef-4219-9a28-2d30eda9bf56" xlink:to="loc_us-gaap_IncomeTaxDisclosureTextBlock_e74111cd-f0df-465b-9e2c-5b7e62555150" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#IncomeTaxesAdditionalInformationDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/IncomeTaxesAdditionalInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxDisclosureAbstract_cac867f6-8f61-4c84-8b9a-ca39741c6178" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_IncomeTaxDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ValuationAllowanceAsPercentageOnDeferredTaxAssets_f23a3e64-6870-4082-912b-bd62182dbdc9" xlink:href="plrx-20220331.xsd#plrx_ValuationAllowanceAsPercentageOnDeferredTaxAssets"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_cac867f6-8f61-4c84-8b9a-ca39741c6178" xlink:to="loc_plrx_ValuationAllowanceAsPercentageOnDeferredTaxAssets_f23a3e64-6870-4082-912b-bd62182dbdc9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_0fcbb073-6fc5-418e-aa0e-d69b2a5e40c0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_IncomeTaxDisclosureAbstract_cac867f6-8f61-4c84-8b9a-ca39741c6178" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_0fcbb073-6fc5-418e-aa0e-d69b2a5e40c0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommitmentsandContingencies" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommitmentsandContingencies"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommitmentsandContingencies" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_845bd1b0-db51-47f7-8ff6-f28a0038c359" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_654f6d84-9992-4dfd-8d86-25c9f0752647" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_845bd1b0-db51-47f7-8ff6-f28a0038c359" xlink:to="loc_us-gaap_CommitmentsAndContingenciesDisclosureTextBlock_654f6d84-9992-4dfd-8d86-25c9f0752647" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_77b0327b-ed22-4455-9ab4-533b81a72764" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ContractualArrangementsCancellationPeriod_f2062ae8-bc43-4d9f-8a1b-fe267dc7e8f8" xlink:href="plrx-20220331.xsd#plrx_ContractualArrangementsCancellationPeriod"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_77b0327b-ed22-4455-9ab4-533b81a72764" xlink:to="loc_plrx_ContractualArrangementsCancellationPeriod_f2062ae8-bc43-4d9f-8a1b-fe267dc7e8f8" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/Leases" xlink:type="simple" xlink:href="plrx-20220331.xsd#Leases"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/Leases" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract_faf924c1-5f8d-42e5-b45f-33cbd77d61b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeasesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeasesTextBlock_fb26c983-20c2-4046-9d2a-5646cab44925" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeasesTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_faf924c1-5f8d-42e5-b45f-33cbd77d61b0" xlink:to="loc_us-gaap_LesseeOperatingLeasesTextBlock_fb26c983-20c2-4046-9d2a-5646cab44925" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/LeasesTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#LeasesTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/LeasesTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract_c216b972-8805-4543-9b16-1460fdc34665" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeasesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_42cf5a4c-aa75-40bc-a819-cf072ea68966" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_c216b972-8805-4543-9b16-1460fdc34665" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityMaturityTableTextBlock_42cf5a4c-aa75-40bc-a819-cf072ea68966" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_AssetsAndLiabilitiesLesseeTableTextBlock_acb1f538-7856-444e-814f-f0dab6440b48" xlink:href="plrx-20220331.xsd#plrx_AssetsAndLiabilitiesLesseeTableTextBlock"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_c216b972-8805-4543-9b16-1460fdc34665" xlink:to="loc_plrx_AssetsAndLiabilitiesLesseeTableTextBlock_acb1f538-7856-444e-814f-f0dab6440b48" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#LeasesNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract_949bd98b-f63d-412e-a60c-9d21be1b716c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeasesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_949bd98b-f63d-412e-a60c-9d21be1b716c" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_abcd7331-2276-4a10-a278-c306fc4d033e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_StatementGeographicalAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:to="loc_srt_StatementGeographicalAxis_abcd7331-2276-4a10-a278-c306fc4d033e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_67143f86-2c1e-4d30-969e-92a01003a175" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_SegmentGeographicalDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_StatementGeographicalAxis_abcd7331-2276-4a10-a278-c306fc4d033e" xlink:to="loc_srt_SegmentGeographicalDomain_67143f86-2c1e-4d30-969e-92a01003a175" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_e9c7fe8b-88a0-4338-aecf-910679699aab" xlink:href="https://xbrl.sec.gov/stpr/2021/stpr-2021.xsd#stpr_CA"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_SegmentGeographicalDomain_67143f86-2c1e-4d30-969e-92a01003a175" xlink:to="loc_stpr_CA_e9c7fe8b-88a0-4338-aecf-910679699aab" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_2dc4910f-e39c-4829-8736-3d6bb4696202" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_2dc4910f-e39c-4829-8736-3d6bb4696202" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_8d758c94-7555-4cbc-af70-cff54425ead4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2dc4910f-e39c-4829-8736-3d6bb4696202" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_8d758c94-7555-4cbc-af70-cff54425ead4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_87f5f8c2-4fd6-48f1-91ab-30c9e069a30c" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_8d758c94-7555-4cbc-af70-cff54425ead4" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_87f5f8c2-4fd6-48f1-91ab-30c9e069a30c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_05800c3a-f3b4-4efc-a7be-4a8ce6d5096e" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:to="loc_srt_RangeAxis_05800c3a-f3b4-4efc-a7be-4a8ce6d5096e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7a1b7071-97be-47d2-9308-984360165e12" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_RangeMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeAxis_05800c3a-f3b4-4efc-a7be-4a8ce6d5096e" xlink:to="loc_srt_RangeMember_7a1b7071-97be-47d2-9308-984360165e12" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_cf7f280b-5ede-4927-a69e-e645cab254a4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MaximumMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_7a1b7071-97be-47d2-9308-984360165e12" xlink:to="loc_srt_MaximumMember_cf7f280b-5ede-4927-a69e-e645cab254a4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1bca0fb1-8448-492d-aaaf-8d41b306d737" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_MinimumMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_RangeMember_7a1b7071-97be-47d2-9308-984360165e12" xlink:to="loc_srt_MinimumMember_1bca0fb1-8448-492d-aaaf-8d41b306d737" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_9459e445-eeae-4a2f-a113-edd63bd0858d" xlink:to="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LeasedSpaceUnderNonCancellableOperatingLease_609ca98f-dab7-4fe2-a4cc-e8b9f33c0f02" xlink:href="plrx-20220331.xsd#plrx_LeasedSpaceUnderNonCancellableOperatingLease"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_plrx_LeasedSpaceUnderNonCancellableOperatingLease_609ca98f-dab7-4fe2-a4cc-e8b9f33c0f02" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_acf918ed-9a7d-4812-9f7c-4d1393bd222f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_acf918ed-9a7d-4812-9f7c-4d1393bd222f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_PeriodOfBaseRentAbatement_5b8e60ca-b1a3-4c40-b49d-650feb456bd6" xlink:href="plrx-20220331.xsd#plrx_PeriodOfBaseRentAbatement"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_plrx_PeriodOfBaseRentAbatement_5b8e60ca-b1a3-4c40-b49d-650feb456bd6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_BaseRentAbatedAmount_07820067-172b-440a-81c8-4c6c4afdd21f" xlink:href="plrx-20220331.xsd#plrx_BaseRentAbatedAmount"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_plrx_BaseRentAbatedAmount_07820067-172b-440a-81c8-4c6c4afdd21f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecurityDeposit_d470dd48-f8ac-4cae-abd6-07ee0a185a1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecurityDeposit"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_SecurityDeposit_d470dd48-f8ac-4cae-abd6-07ee0a185a1a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_1493c821-2fa5-41c8-810b-84edaab8ff07" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_1493c821-2fa5-41c8-810b-84edaab8ff07" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LeaseTermExtensionNoticePeriod_644178f1-9358-490b-99f2-cead035a031f" xlink:href="plrx-20220331.xsd#plrx_LeaseTermExtensionNoticePeriod"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_plrx_LeaseTermExtensionNoticePeriod_644178f1-9358-490b-99f2-cead035a031f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseCost_2b35d5d8-9136-4c50-ab79-4af0aee75080" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseCost"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_OperatingLeaseCost_2b35d5d8-9136-4c50-ab79-4af0aee75080" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableLeaseCost_7b54af51-48b9-42b9-bf7f-dd6bde8b0ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableLeaseCost"/>
    <link:presentationArc order="9" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_VariableLeaseCost_7b54af51-48b9-42b9-bf7f-dd6bde8b0ebc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeasePayments_ecbe3b8f-5587-44c4-9464-9d57d748f5d7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeasePayments"/>
    <link:presentationArc order="10" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_b2db4697-58b4-4e37-ac7b-0df675518426" xlink:to="loc_us-gaap_OperatingLeasePayments_ecbe3b8f-5587-44c4-9464-9d57d748f5d7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/LeasesScheduleofOperatingLeaseLiabilityDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#LeasesScheduleofOperatingLeaseLiabilityDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/LeasesScheduleofOperatingLeaseLiabilityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract_1403d128-68d6-485d-988a-d95b293d3c17" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeasesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_1403d128-68d6-485d-988a-d95b293d3c17" xlink:to="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_ad9febf6-cdf8-490c-ae8a-75f905c42d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_ad9febf6-cdf8-490c-ae8a-75f905c42d8d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9e17611a-07fd-4d0c-8d47-dbd87c52bca9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths_9e17611a-07fd-4d0c-8d47-dbd87c52bca9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_fbd93ede-c235-4da5-ae92-74e8f8aed246" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_fbd93ede-c235-4da5-ae92-74e8f8aed246" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_0846f435-e312-4ee5-9463-e9f02c1c3b50" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_0846f435-e312-4ee5-9463-e9f02c1c3b50" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_7ae59fee-9e34-4085-b070-6afb4e7565b2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_7ae59fee-9e34-4085-b070-6afb4e7565b2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0aee0f25-5c69-4c90-9235-906e9c923256" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0aee0f25-5c69-4c90-9235-906e9c923256" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/totalLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_86cb9060-ebef-42a8-a127-0234ffba011d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount"/>
    <link:presentationArc order="7" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_86cb9060-ebef-42a8-a127-0234ffba011d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiability_4a5c9b80-91da-4e3d-8299-3ad21a66adf7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseLiability"/>
    <link:presentationArc order="8" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_e79e5506-e2cb-4cbf-a35f-c9e8b2fbedea" xlink:to="loc_us-gaap_OperatingLeaseLiability_4a5c9b80-91da-4e3d-8299-3ad21a66adf7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/LeasesScheduleofOperatingLeaseLiabilityDetails_1" xlink:type="simple" xlink:href="plrx-20220331.xsd#LeasesScheduleofOperatingLeaseLiabilityDetails_1"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/LeasesScheduleofOperatingLeaseLiabilityDetails_1" xlink:type="extended"/>
  <link:roleRef roleURI="http://www.pliantrx.com/role/LeasesWeightedaverageRemainingLeaseTermsandDiscountRatesDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#LeasesWeightedaverageRemainingLeaseTermsandDiscountRatesDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/LeasesWeightedaverageRemainingLeaseTermsandDiscountRatesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeasesAbstract_b1974fc2-3c0d-4f27-8764-2ed7ab4ac834" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LeasesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_d65d382b-5204-4ed7-83c9-380811dea9cc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_b1974fc2-3c0d-4f27-8764-2ed7ab4ac834" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1_d65d382b-5204-4ed7-83c9-380811dea9cc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_0f50367e-5450-4481-a118-b06302d7d2ec" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LeasesAbstract_b1974fc2-3c0d-4f27-8764-2ed7ab4ac834" xlink:to="loc_us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent_0f50367e-5450-4481-a118-b06302d7d2ec" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RelatedPartyTransactions" xlink:type="simple" xlink:href="plrx-20220331.xsd#RelatedPartyTransactions"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RelatedPartyTransactions" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsAbstract_7c2639a2-c9a8-4cb6-9ca5-370654ea6e33" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_f9e0e057-266b-472e-9b59-3ad1aaa15396" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsDisclosureTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsAbstract_7c2639a2-c9a8-4cb6-9ca5-370654ea6e33" xlink:to="loc_us-gaap_RelatedPartyTransactionsDisclosureTextBlock_f9e0e057-266b-472e-9b59-3ad1aaa15396" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/RelatedPartyTransactionsNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#RelatedPartyTransactionsNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/RelatedPartyTransactionsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsAbstract_f2baa3fc-681d-4e81-b259-f1598aeb0c84" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionsAbstract_f2baa3fc-681d-4e81-b259-f1598aeb0c84" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionAxis_ca1a19c3-8200-4ca7-a43b-5cb4642666d3" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:to="loc_us-gaap_RelatedPartyTransactionAxis_ca1a19c3-8200-4ca7-a43b-5cb4642666d3" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionDomain_4fb8c76e-794b-4838-906c-7814711c8551" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionAxis_ca1a19c3-8200-4ca7-a43b-5cb4642666d3" xlink:to="loc_us-gaap_RelatedPartyTransactionDomain_4fb8c76e-794b-4838-906c-7814711c8551" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ThirdRockVenturesMember_96e4403b-b0dd-4006-8ad7-c99b6497be83" xlink:href="plrx-20220331.xsd#plrx_ThirdRockVenturesMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionDomain_4fb8c76e-794b-4838-906c-7814711c8551" xlink:to="loc_plrx_ThirdRockVenturesMember_96e4403b-b0dd-4006-8ad7-c99b6497be83" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_a28cc226-415e-44a7-b20d-4bc67289fc88" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:to="loc_srt_TitleOfIndividualAxis_a28cc226-415e-44a7-b20d-4bc67289fc88" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_c2f22c47-a410-4b49-aacc-658f73866df4" xlink:href="https://xbrl.fasb.org/srt/2021/elts/srt-2021-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_TitleOfIndividualAxis_a28cc226-415e-44a7-b20d-4bc67289fc88" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_c2f22c47-a410-4b49-aacc-658f73866df4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_NonemployeeDirectorMember_018596fa-f81d-44c2-a239-9f970b61feff" xlink:href="plrx-20220331.xsd#plrx_NonemployeeDirectorMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_c2f22c47-a410-4b49-aacc-658f73866df4" xlink:to="loc_plrx_NonemployeeDirectorMember_018596fa-f81d-44c2-a239-9f970b61feff" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_5f454de7-1ca6-484d-830b-07b0df7c7036" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AwardTypeAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:to="loc_us-gaap_AwardTypeAxis_5f454de7-1ca6-484d-830b-07b0df7c7036" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c26e8ce1-c883-4326-b14a-496bd3c8a907" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AwardTypeAxis_5f454de7-1ca6-484d-830b-07b0df7c7036" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c26e8ce1-c883-4326-b14a-496bd3c8a907" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_e024eda2-7cbe-479c-85f4-435aba82aa4e" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_c26e8ce1-c883-4326-b14a-496bd3c8a907" xlink:to="loc_us-gaap_EmployeeStockOptionMember_e024eda2-7cbe-479c-85f4-435aba82aa4e" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_d1a3e512-16f2-4273-a955-9c2211288708" xlink:to="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_4a07974b-7326-4fd9-84c5-def22e811d77" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_4a07974b-7326-4fd9-84c5-def22e811d77" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue_a220cc79-a05a-43e4-904e-edfc74cba17a" xlink:href="plrx-20220331.xsd#plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:to="loc_plrx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue_a220cc79-a05a-43e4-904e-edfc74cba17a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_a387829a-4df4-48e0-b179-3a2f335cfd90" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_a387829a-4df4-48e0-b179-3a2f335cfd90" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights_ec45b5e5-1c2b-498c-acb4-4dc736750780" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_944420b3-4d83-441c-afda-19a6511005c1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingRights_ec45b5e5-1c2b-498c-acb4-4dc736750780" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/DefinedContributionPlan" xlink:type="simple" xlink:href="plrx-20220331.xsd#DefinedContributionPlan"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/DefinedContributionPlan" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CompensationAndRetirementDisclosureAbstract_3fa040c4-9bf6-4f11-8898-674814137e5d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CompensationAndRetirementDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanTextBlock_aa997cb4-ada2-4dfe-8881-0379dc9af3c1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CompensationAndRetirementDisclosureAbstract_3fa040c4-9bf6-4f11-8898-674814137e5d" xlink:to="loc_us-gaap_DefinedContributionPlanTextBlock_aa997cb4-ada2-4dfe-8881-0379dc9af3c1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/DefinedContributionPlanNarrativeDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#DefinedContributionPlanNarrativeDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/DefinedContributionPlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CompensationAndRetirementDisclosureAbstract_394c5c6a-80d6-4539-93b5-9442ed434bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_CompensationAndRetirementDisclosureAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_f04da994-b91c-4f03-80e3-12073df2a574" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_CompensationAndRetirementDisclosureAbstract_394c5c6a-80d6-4539-93b5-9442ed434bdc" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_f04da994-b91c-4f03-80e3-12073df2a574" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholders" xlink:type="simple" xlink:href="plrx-20220331.xsd#NetLossPerShareAttributabletoCommonStockholders"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholders" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_1055f8b6-8b12-4598-aec6-efa52f5792a5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareTextBlock_17a129a6-904a-44e9-b10c-f162d435d5b6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_1055f8b6-8b12-4598-aec6-efa52f5792a5" xlink:to="loc_us-gaap_EarningsPerShareTextBlock_17a129a6-904a-44e9-b10c-f162d435d5b6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersTables" xlink:type="simple" xlink:href="plrx-20220331.xsd#NetLossPerShareAttributabletoCommonStockholdersTables"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersTables" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_7e153654-e79f-4aa2-90d9-0956db3792ad" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_fa298458-d876-4d39-b53d-8d43819c9262" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7e153654-e79f-4aa2-90d9-0956db3792ad" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTextBlock_fa298458-d876-4d39-b53d-8d43819c9262" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_8d738cf0-df94-4855-aab9-741acd5f22aa" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_7e153654-e79f-4aa2-90d9-0956db3792ad" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock_8d738cf0-df94-4855-aab9-741acd5f22aa" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#NetLossPerShareAttributabletoCommonStockholdersSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersSummaryofPotentiallyDilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_3bfc56fe-ad13-4f9c-afde-9edc28a4c2b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_00b0e01b-6908-45be-bbdc-a343222e90f2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_3bfc56fe-ad13-4f9c-afde-9edc28a4c2b0" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_00b0e01b-6908-45be-bbdc-a343222e90f2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_945628fd-cb70-4066-8041-b62e017527f1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_00b0e01b-6908-45be-bbdc-a343222e90f2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_945628fd-cb70-4066-8041-b62e017527f1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f7b83777-2cc1-44dd-aa6e-2999ead72404" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_945628fd-cb70-4066-8041-b62e017527f1" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f7b83777-2cc1-44dd-aa6e-2999ead72404" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_6c50b803-0637-4328-ac4b-08089f6cd80d" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f7b83777-2cc1-44dd-aa6e-2999ead72404" xlink:to="loc_us-gaap_EmployeeStockOptionMember_6c50b803-0637-4328-ac4b-08089f6cd80d" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_RestrictedStockAwardsGrantedAndNotPurchasedMember_ff92aa5d-6ba9-4f8c-94bb-2c3df1307f6a" xlink:href="plrx-20220331.xsd#plrx_RestrictedStockAwardsGrantedAndNotPurchasedMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f7b83777-2cc1-44dd-aa6e-2999ead72404" xlink:to="loc_plrx_RestrictedStockAwardsGrantedAndNotPurchasedMember_ff92aa5d-6ba9-4f8c-94bb-2c3df1307f6a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_c2c58ad7-5c6b-460f-8258-a5f9774417c4" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_RestrictedStockMember"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_f7b83777-2cc1-44dd-aa6e-2999ead72404" xlink:to="loc_us-gaap_RestrictedStockMember_c2c58ad7-5c6b-460f-8258-a5f9774417c4" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/verboseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52a2dd71-0cb0-48df-881a-bbcf54252674" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_00b0e01b-6908-45be-bbdc-a343222e90f2" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52a2dd71-0cb0-48df-881a-bbcf54252674" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_e6632e4b-bd72-4a57-a3d3-82e635bc2a84" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_52a2dd71-0cb0-48df-881a-bbcf54252674" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_e6632e4b-bd72-4a57-a3d3-82e635bc2a84" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersReconciliationofNumeratorandDenominatorUsedinCalculationofBasicandDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#NetLossPerShareAttributabletoCommonStockholdersReconciliationofNumeratorandDenominatorUsedinCalculationofBasicandDilutedNetLossPerShareDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/NetLossPerShareAttributabletoCommonStockholdersReconciliationofNumeratorandDenominatorUsedinCalculationofBasicandDilutedNetLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_5443c929-fa62-45b6-a048-e49ddafceb1a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareReconciliationAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4260d844-3e69-4482-93bd-6cbf2cfd8bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_5443c929-fa62-45b6-a048-e49ddafceb1a" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4260d844-3e69-4482-93bd-6cbf2cfd8bf1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_1abc9766-3e1e-4e2b-8387-109b555ac8b9" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_NetIncomeLoss"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_4260d844-3e69-4482-93bd-6cbf2cfd8bf1" xlink:to="loc_us-gaap_NetIncomeLoss_1abc9766-3e1e-4e2b-8387-109b555ac8b9" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_108d7ae6-66b5-40b9-899a-fa5aca062ea0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_5443c929-fa62-45b6-a048-e49ddafceb1a" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_108d7ae6-66b5-40b9-899a-fa5aca062ea0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ea1f516e-5e59-4443-9ffb-6fd23e614a36" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_108d7ae6-66b5-40b9-899a-fa5aca062ea0" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_ea1f516e-5e59-4443-9ffb-6fd23e614a36" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_3aeca4b8-384f-49cf-952f-7671b6991706" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_108d7ae6-66b5-40b9-899a-fa5aca062ea0" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_3aeca4b8-384f-49cf-952f-7671b6991706" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_caa7e16a-3883-4407-8b12-fb2049891869" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_5443c929-fa62-45b6-a048-e49ddafceb1a" xlink:to="loc_us-gaap_EarningsPerShareAbstract_caa7e16a-3883-4407-8b12-fb2049891869" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_7eab97b9-f155-456a-9a6e-2ee83a01f58a" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_caa7e16a-3883-4407-8b12-fb2049891869" xlink:to="loc_us-gaap_EarningsPerShareBasic_7eab97b9-f155-456a-9a6e-2ee83a01f58a" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_d6844c27-603c-4259-a15d-fac237d523e5" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_EarningsPerShareAbstract_caa7e16a-3883-4407-8b12-fb2049891869" xlink:to="loc_us-gaap_EarningsPerShareDiluted_d6844c27-603c-4259-a15d-fac237d523e5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/SubsequentEvents" xlink:type="simple" xlink:href="plrx-20220331.xsd#SubsequentEvents"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/SubsequentEvents" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsAbstract_e85a70b9-2c6f-46e0-a2ff-658e8166a7b8" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsTextBlock_e6469c27-87c3-4358-85e6-e03f50678158" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventsTextBlock"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventsAbstract_e85a70b9-2c6f-46e0-a2ff-658e8166a7b8" xlink:to="loc_us-gaap_SubsequentEventsTextBlock_e6469c27-87c3-4358-85e6-e03f50678158" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
  <link:roleRef roleURI="http://www.pliantrx.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="plrx-20220331.xsd#SubsequentEventsDetails"/>
  <link:presentationLink xlink:role="http://www.pliantrx.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventsAbstract_de2e67f5-d528-4cac-9d71-878f967acafe" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTable"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventsAbstract_de2e67f5-d528-4cac-9d71-878f967acafe" xlink:to="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_32576389-1311-4614-87dc-cac3b67bad17" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_32576389-1311-4614-87dc-cac3b67bad17" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_2a1a9713-c7ac-4256-9450-1c480df413f7" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_32576389-1311-4614-87dc-cac3b67bad17" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_2a1a9713-c7ac-4256-9450-1c480df413f7" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_695d2ff8-8e3a-4d96-a58b-8755dd1654a6" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_2a1a9713-c7ac-4256-9450-1c480df413f7" xlink:to="loc_us-gaap_SubsequentEventMember_695d2ff8-8e3a-4d96-a58b-8755dd1654a6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_a7ee271f-89ab-4863-80e5-dda0427692bc" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_a7ee271f-89ab-4863-80e5-dda0427692bc" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_a3282415-59fc-45d0-a686-c3a891deb214" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_a7ee271f-89ab-4863-80e5-dda0427692bc" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_a3282415-59fc-45d0-a686-c3a891deb214" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_TermLoanFacilityMember_79a01f97-f148-42d9-ac39-1355578ff31c" xlink:href="plrx-20220331.xsd#plrx_TermLoanFacilityMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_a3282415-59fc-45d0-a686-c3a891deb214" xlink:to="loc_plrx_TermLoanFacilityMember_79a01f97-f148-42d9-ac39-1355578ff31c" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_f38dcbb7-63cd-438c-bbfd-95434aa10fdb" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_us-gaap_DebtInstrumentAxis_f38dcbb7-63cd-438c-bbfd-95434aa10fdb" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7f6a6116-e53b-4a21-b563-1ad999aa5873" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentAxis_f38dcbb7-63cd-438c-bbfd-95434aa10fdb" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7f6a6116-e53b-4a21-b563-1ad999aa5873" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_LoanAgreementMember_6b980e06-df52-414b-be99-c0126ebbaaa6" xlink:href="plrx-20220331.xsd#plrx_LoanAgreementMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_7f6a6116-e53b-4a21-b563-1ad999aa5873" xlink:to="loc_plrx_LoanAgreementMember_6b980e06-df52-414b-be99-c0126ebbaaa6" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtDrawPeriodAxis_b99df967-127b-46d7-a176-593958d150ba" xlink:href="plrx-20220331.xsd#plrx_DebtDrawPeriodAxis"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_plrx_DebtDrawPeriodAxis_b99df967-127b-46d7-a176-593958d150ba" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtDrawPeriodDomain_7d6245b4-f06e-4466-b078-fbf88f470688" xlink:href="plrx-20220331.xsd#plrx_DebtDrawPeriodDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_DebtDrawPeriodAxis_b99df967-127b-46d7-a176-593958d150ba" xlink:to="loc_plrx_DebtDrawPeriodDomain_7d6245b4-f06e-4466-b078-fbf88f470688" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtDrawTrancheOneMember_37b35176-3bac-4f28-851b-38d9ca7ff2af" xlink:href="plrx-20220331.xsd#plrx_DebtDrawTrancheOneMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_DebtDrawPeriodDomain_7d6245b4-f06e-4466-b078-fbf88f470688" xlink:to="loc_plrx_DebtDrawTrancheOneMember_37b35176-3bac-4f28-851b-38d9ca7ff2af" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtDrawTrancheTwoMember_721b55f4-1e26-4b79-82f7-6728f8075ae5" xlink:href="plrx-20220331.xsd#plrx_DebtDrawTrancheTwoMember"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_DebtDrawPeriodDomain_7d6245b4-f06e-4466-b078-fbf88f470688" xlink:to="loc_plrx_DebtDrawTrancheTwoMember_721b55f4-1e26-4b79-82f7-6728f8075ae5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtDrawTrancheThreeMember_ab2558b8-7579-4b17-a1d5-d91ca7e1f6c1" xlink:href="plrx-20220331.xsd#plrx_DebtDrawTrancheThreeMember"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_plrx_DebtDrawPeriodDomain_7d6245b4-f06e-4466-b078-fbf88f470688" xlink:to="loc_plrx_DebtDrawTrancheThreeMember_ab2558b8-7579-4b17-a1d5-d91ca7e1f6c1" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_e70927a4-a73f-431c-9e47-11702c01c69f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateAxis"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_us-gaap_VariableRateAxis_e70927a4-a73f-431c-9e47-11702c01c69f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_fdf1fe69-b7a5-4035-87de-d9c16b16a988" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_VariableRateDomain"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_VariableRateAxis_e70927a4-a73f-431c-9e47-11702c01c69f" xlink:to="loc_us-gaap_VariableRateDomain_fdf1fe69-b7a5-4035-87de-d9c16b16a988" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_2545f846-8499-4db3-8998-748873f34439" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_VariableRateDomain_fdf1fe69-b7a5-4035-87de-d9c16b16a988" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_2545f846-8499-4db3-8998-748873f34439" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:presentationArc order="6" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventTable_b887be81-7bcc-41ed-a204-1bb5c8271c30" xlink:to="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_0a7a55ee-386a-4926-8461-dbfca94be411" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:presentationArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_0a7a55ee-386a-4926-8461-dbfca94be411" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfDebt_dde6fc9b-c18d-4ef6-8ad9-421c00a3c48f" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_ProceedsFromIssuanceOfDebt"/>
    <link:presentationArc order="2" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfDebt_dde6fc9b-c18d-4ef6-8ad9-421c00a3c48f" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtInstrumentTrancheOneAmountUndrawn_3c2cf2c7-10bb-4b0d-a593-187ef17c7bf5" xlink:href="plrx-20220331.xsd#plrx_DebtInstrumentTrancheOneAmountUndrawn"/>
    <link:presentationArc order="3" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:to="loc_plrx_DebtInstrumentTrancheOneAmountUndrawn_3c2cf2c7-10bb-4b0d-a593-187ef17c7bf5" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_plrx_DebtInstrumentAmountAvailableAfterTrancheOne_65b7b574-a7f1-4a87-9908-21d7dcfa6aaf" xlink:href="plrx-20220331.xsd#plrx_DebtInstrumentAmountAvailableAfterTrancheOne"/>
    <link:presentationArc order="4" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:to="loc_plrx_DebtInstrumentAmountAvailableAfterTrancheOne_65b7b574-a7f1-4a87-9908-21d7dcfa6aaf" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_b0985e77-1514-4eb6-b3c0-f170268b15b0" xlink:href="https://xbrl.fasb.org/us-gaap/2021/elts/us-gaap-2021-01-31.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:presentationArc order="5" xlink:arcrole="http://www.xbrl.org/2003/arcrole/parent-child" xlink:from="loc_us-gaap_SubsequentEventLineItems_1e883333-6a40-4c39-9b6b-4329962192d2" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_b0985e77-1514-4eb6-b3c0-f170268b15b0" xlink:type="arc" preferredLabel="http://www.xbrl.org/2003/role/terseLabel"/>
  </link:presentationLink>
</link:linkbase>
