diff --git a/clang-tools-extra/clang-doc/tool/CMakeLists.txt b/clang-tools-extra/clang-doc/tool/CMakeLists.txt
--- a/clang-tools-extra/clang-doc/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-doc/tool/CMakeLists.txt
@@ -19,9 +19,9 @@
   )
 
 install(FILES ../assets/clang-doc-default-stylesheet.css
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-doc)
 
 install(FILES ../assets/index.js
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-doc)
diff --git a/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt b/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
--- a/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/CMakeLists.txt
@@ -20,5 +20,5 @@
   )
 
 install(PROGRAMS run-find-all-symbols.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT find-all-symbols)
diff --git a/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt b/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
--- a/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-include-fixer/tool/CMakeLists.txt
@@ -21,8 +21,8 @@
   )
 
 install(PROGRAMS clang-include-fixer.el
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-include-fixer)
 install(PROGRAMS clang-include-fixer.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-include-fixer)
diff --git a/clang-tools-extra/clang-tidy/CMakeLists.txt b/clang-tools-extra/clang-tidy/CMakeLists.txt
--- a/clang-tools-extra/clang-tidy/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/CMakeLists.txt
@@ -113,7 +113,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY .
-    DESTINATION include/clang-tidy
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/clang-tidy"
     COMPONENT clang-tidy-headers
     FILES_MATCHING
     PATTERN "*.h"
diff --git a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
--- a/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
+++ b/clang-tools-extra/clang-tidy/tool/CMakeLists.txt
@@ -52,9 +52,9 @@
 
 
 install(PROGRAMS clang-tidy-diff.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-tidy)
 install(PROGRAMS run-clang-tidy.py
-  DESTINATION bin
+  DESTINATION "${CMAKE_INSTALL_BINDIR}"
   COMPONENT clang-tidy
   RENAME run-clang-tidy)
diff --git a/clang-tools-extra/modularize/CMakeLists.txt b/clang-tools-extra/modularize/CMakeLists.txt
--- a/clang-tools-extra/modularize/CMakeLists.txt
+++ b/clang-tools-extra/modularize/CMakeLists.txt
@@ -23,5 +23,5 @@
   )
 
 install(TARGETS modularize
-        RUNTIME DESTINATION bin
+        RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
         COMPONENT clang-extras)
diff --git a/clang/CMakeLists.txt b/clang/CMakeLists.txt
--- a/clang/CMakeLists.txt
+++ b/clang/CMakeLists.txt
@@ -4,7 +4,11 @@
 # standalone project, using LLVM as an external library:
 if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   project(Clang)
+endif()
+
+include(GNUInstallDirs)
 
+if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
   set(CMAKE_CXX_STANDARD_REQUIRED YES)
   set(CMAKE_CXX_EXTENSIONS NO)
@@ -418,7 +422,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/clang include/clang-c
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT clang-headers
     FILES_MATCHING
     PATTERN "*.def"
@@ -427,7 +431,7 @@
     )
 
   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/include/clang
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT clang-headers
     FILES_MATCHING
     PATTERN "CMakeFiles" EXCLUDE
@@ -447,7 +451,7 @@
 
   add_custom_target(bash-autocomplete DEPENDS utils/bash-autocomplete.sh)
   install(PROGRAMS utils/bash-autocomplete.sh
-          DESTINATION share/clang
+          DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
           COMPONENT bash-autocomplete)
   if(NOT LLVM_ENABLE_IDE)
     add_llvm_install_targets(install-bash-autocomplete
diff --git a/clang/cmake/modules/AddClang.cmake b/clang/cmake/modules/AddClang.cmake
--- a/clang/cmake/modules/AddClang.cmake
+++ b/clang/cmake/modules/AddClang.cmake
@@ -125,7 +125,7 @@
           ${export_to_clangtargets}
           LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
           ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-          RUNTIME DESTINATION bin)
+          RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
         if (NOT LLVM_ENABLE_IDE)
           add_llvm_install_targets(install-${lib}
@@ -170,7 +170,7 @@
 
     install(TARGETS ${name}
       ${export_to_clangtargets}
-      RUNTIME DESTINATION bin
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
       COMPONENT ${name})
 
     if(NOT LLVM_ENABLE_IDE)
diff --git a/clang/tools/c-index-test/CMakeLists.txt b/clang/tools/c-index-test/CMakeLists.txt
--- a/clang/tools/c-index-test/CMakeLists.txt
+++ b/clang/tools/c-index-test/CMakeLists.txt
@@ -54,7 +54,7 @@
     set_property(TARGET c-index-test APPEND PROPERTY INSTALL_RPATH
        "@executable_path/../../lib")
   else()
-    set(INSTALL_DESTINATION bin)
+    set(INSTALL_DESTINATION "${CMAKE_INSTALL_BINDIR}")
   endif()
 
   install(TARGETS c-index-test
diff --git a/clang/tools/clang-format/CMakeLists.txt b/clang/tools/clang-format/CMakeLists.txt
--- a/clang/tools/clang-format/CMakeLists.txt
+++ b/clang/tools/clang-format/CMakeLists.txt
@@ -21,20 +21,20 @@
 endif()
 
 install(PROGRAMS clang-format-bbedit.applescript
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-format)
 install(PROGRAMS clang-format-diff.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-format)
 install(PROGRAMS clang-format-sublime.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-format)
 install(PROGRAMS clang-format.el
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-format)
 install(PROGRAMS clang-format.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-format)
 install(PROGRAMS git-clang-format
-  DESTINATION bin
+  DESTINATION "${CMAKE_INSTALL_BINDIR}"
   COMPONENT clang-format)
diff --git a/clang/tools/clang-rename/CMakeLists.txt b/clang/tools/clang-rename/CMakeLists.txt
--- a/clang/tools/clang-rename/CMakeLists.txt
+++ b/clang/tools/clang-rename/CMakeLists.txt
@@ -19,8 +19,8 @@
   )
 
 install(PROGRAMS clang-rename.py
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-rename)
 install(PROGRAMS clang-rename.el
-  DESTINATION share/clang
+  DESTINATION "${CMAKE_INSTALL_DATADIR}/clang"
   COMPONENT clang-rename)
diff --git a/clang/tools/libclang/CMakeLists.txt b/clang/tools/libclang/CMakeLists.txt
--- a/clang/tools/libclang/CMakeLists.txt
+++ b/clang/tools/libclang/CMakeLists.txt
@@ -150,7 +150,7 @@
 if(INTERNAL_INSTALL_PREFIX)
   set(LIBCLANG_HEADERS_INSTALL_DESTINATION "${INTERNAL_INSTALL_PREFIX}/include")
 else()
-  set(LIBCLANG_HEADERS_INSTALL_DESTINATION include)
+  set(LIBCLANG_HEADERS_INSTALL_DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 endif()
 
 install(DIRECTORY ../../include/clang-c
diff --git a/clang/tools/scan-build/CMakeLists.txt b/clang/tools/scan-build/CMakeLists.txt
--- a/clang/tools/scan-build/CMakeLists.txt
+++ b/clang/tools/scan-build/CMakeLists.txt
@@ -47,7 +47,7 @@
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BinFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/bin/${BinFile})
     install(PROGRAMS bin/${BinFile}
-            DESTINATION bin
+            DESTINATION "${CMAKE_INSTALL_BINDIR}"
             COMPONENT scan-build)
   endforeach()
 
@@ -61,7 +61,7 @@
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/libexec/${LibexecFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/libexec/${LibexecFile})
     install(PROGRAMS libexec/${LibexecFile}
-            DESTINATION libexec
+            DESTINATION "${CMAKE_INSTALL_LIBEXECDIR}"
             COMPONENT scan-build)
   endforeach()
 
@@ -89,7 +89,7 @@
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/share/scan-build/${ShareFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/share/scan-build/${ShareFile})
     install(FILES share/scan-build/${ShareFile}
-            DESTINATION share/scan-build
+            DESTINATION "${CMAKE_INSTALL_DATADIR}/scan-build"
             COMPONENT scan-build)
   endforeach()
 
diff --git a/clang/tools/scan-view/CMakeLists.txt b/clang/tools/scan-view/CMakeLists.txt
--- a/clang/tools/scan-view/CMakeLists.txt
+++ b/clang/tools/scan-view/CMakeLists.txt
@@ -20,7 +20,7 @@
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/bin/${BinFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/bin/${BinFile})
     install(PROGRAMS bin/${BinFile}
-            DESTINATION bin
+            DESTINATION "${CMAKE_INSTALL_BINDIR}"
             COMPONENT scan-view)
   endforeach()
 
@@ -34,7 +34,7 @@
                        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/share/${ShareFile})
     list(APPEND Depends ${CMAKE_BINARY_DIR}/share/scan-view/${ShareFile})
     install(FILES share/${ShareFile}
-            DESTINATION share/scan-view
+            DESTINATION "${CMAKE_INSTALL_DATADIR}/scan-view"
             COMPONENT scan-view)
   endforeach()
 
diff --git a/clang/utils/hmaptool/CMakeLists.txt b/clang/utils/hmaptool/CMakeLists.txt
--- a/clang/utils/hmaptool/CMakeLists.txt
+++ b/clang/utils/hmaptool/CMakeLists.txt
@@ -10,7 +10,7 @@
 
 list(APPEND Depends ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin/${CLANG_HMAPTOOL})
 install(PROGRAMS ${CLANG_HMAPTOOL}
-        DESTINATION bin
+        DESTINATION "${CMAKE_INSTALL_BINDIR}"
         COMPONENT hmaptool)
 
 add_custom_target(hmaptool ALL DEPENDS ${Depends})
diff --git a/flang/CMakeLists.txt b/flang/CMakeLists.txt
--- a/flang/CMakeLists.txt
+++ b/flang/CMakeLists.txt
@@ -9,6 +9,8 @@
 set(CMAKE_CXX_STANDARD_REQUIRED TRUE)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+include(GNUInstallDirs)
+
 set(FLANG_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR AND NOT MSVC_IDE)
@@ -437,7 +439,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/flang
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT flang-headers
     FILES_MATCHING
     PATTERN "*.def"
diff --git a/flang/cmake/modules/AddFlang.cmake b/flang/cmake/modules/AddFlang.cmake
--- a/flang/cmake/modules/AddFlang.cmake
+++ b/flang/cmake/modules/AddFlang.cmake
@@ -76,7 +76,7 @@
         ${export_to_flangtargets}
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-        RUNTIME DESTINATION bin)
+        RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
       if (NOT LLVM_ENABLE_IDE)
         add_llvm_install_targets(install-${name}
@@ -119,7 +119,7 @@
 
     install(TARGETS ${name}
       ${export_to_flangtargets}
-      RUNTIME DESTINATION bin
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
       COMPONENT ${name})
 
     if(NOT LLVM_ENABLE_IDE)
diff --git a/flang/tools/f18/CMakeLists.txt b/flang/tools/f18/CMakeLists.txt
--- a/flang/tools/f18/CMakeLists.txt
+++ b/flang/tools/f18/CMakeLists.txt
@@ -55,17 +55,17 @@
     DEPENDS ${base}.mod
     COMMAND ${CMAKE_COMMAND} -E copy ${base}.mod ${base}.f18.mod)
   list(APPEND MODULE_FILES ${base}.mod ${base}.f18.mod)
-  install(FILES ${base}.mod ${base}.f18.mod DESTINATION include/flang)
+  install(FILES ${base}.mod ${base}.f18.mod DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/flang")
 endforeach()
 
 add_custom_target(module_files ALL DEPENDS ${MODULE_FILES})
 
-install(TARGETS f18 DESTINATION bin)
+install(TARGETS f18 DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
 # This flang shell script will only work in a POSIX shell.
 if (NOT WIN32)
   file(COPY ${CMAKE_CURRENT_SOURCE_DIR}/flang
     DESTINATION ${CMAKE_BINARY_DIR}/bin
     FILE_PERMISSIONS OWNER_EXECUTE OWNER_READ OWNER_WRITE)
-  install(PROGRAMS ${CMAKE_BINARY_DIR}/bin/flang DESTINATION bin)
+  install(PROGRAMS ${CMAKE_BINARY_DIR}/bin/flang DESTINATION "${CMAKE_INSTALL_BINDIR}")
 endif()
diff --git a/flang/tools/flang-driver/CMakeLists.txt b/flang/tools/flang-driver/CMakeLists.txt
--- a/flang/tools/flang-driver/CMakeLists.txt
+++ b/flang/tools/flang-driver/CMakeLists.txt
@@ -27,4 +27,4 @@
   clangBasic
 )
 
-install(TARGETS flang-new DESTINATION bin)
+install(TARGETS flang-new DESTINATION "${CMAKE_INSTALL_BINDIR}")
diff --git a/libc/CMakeLists.txt b/libc/CMakeLists.txt
--- a/libc/CMakeLists.txt
+++ b/libc/CMakeLists.txt
@@ -1,5 +1,7 @@
 cmake_minimum_required(VERSION 3.13.4)
 
+include(GNUInstallDirs)
+
 # Use old version of target_sources command which converts the source
 # file paths to full paths.
 cmake_policy(SET CMP0076 OLD)
diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -27,7 +27,11 @@
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXX_STANDALONE_BUILD)
   project(libcxx CXX C)
+endif()
+
+include(GNUInstallDirs)
 
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXX_STANDALONE_BUILD)
   set(PACKAGE_NAME libcxx)
   set(PACKAGE_VERSION 13.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
@@ -410,8 +414,8 @@
   set(LIBCXX_GENERATED_INCLUDE_DIR "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LLVM_BINARY_DIR}/include/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE})
-  set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1")
-  set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "include/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1")
+  set(LIBCXX_INSTALL_INCLUDE_DIR "${CMAKE_INSTALL_INCLUDEDIR}/c++/v1")
+  set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${CMAKE_INSTALL_INCLUDEDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1")
   if(LIBCXX_LIBDIR_SUBDIR)
     string(APPEND LIBCXX_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
     string(APPEND LIBCXX_INSTALL_LIBRARY_DIR /${LIBCXX_LIBDIR_SUBDIR})
@@ -421,14 +425,14 @@
   set(LIBCXX_GENERATED_INCLUDE_DIR "${LLVM_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LIBCXX_GENERATED_INCLUDE_DIR}")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
-  set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1")
+  set(LIBCXX_INSTALL_INCLUDE_DIR "${CMAKE_INSTALL_INCLUDEDIR}/c++/v1")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${LIBCXX_INSTALL_INCLUDE_DIR}")
 else()
   set(LIBCXX_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBCXX_LIBDIR_SUFFIX})
   set(LIBCXX_GENERATED_INCLUDE_DIR "${CMAKE_BINARY_DIR}/include/c++/v1")
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LIBCXX_GENERATED_INCLUDE_DIR}")
   set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX})
-  set(LIBCXX_INSTALL_INCLUDE_DIR "include/c++/v1")
+  set(LIBCXX_INSTALL_INCLUDE_DIR "${CMAKE_INSTALL_INCLUDEDIR}/c++/v1")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${LIBCXX_INSTALL_INCLUDE_DIR}")
 endif()
 
diff --git a/libcxx/cmake/Modules/HandleLibCXXABI.cmake b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
--- a/libcxx/cmake/Modules/HandleLibCXXABI.cmake
+++ b/libcxx/cmake/Modules/HandleLibCXXABI.cmake
@@ -63,7 +63,7 @@
 
         if (LIBCXX_INSTALL_HEADERS)
           install(FILES "${LIBCXX_BINARY_INCLUDE_DIR}/${fpath}"
-            DESTINATION include/c++/v1/${dstdir}
+            DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/c++/v1/${dstdir}"
             COMPONENT cxx-headers
             PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
             )
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -239,7 +239,7 @@
   foreach(file ${files})
     get_filename_component(dir ${file} DIRECTORY)
     install(FILES ${file}
-      DESTINATION ${LIBCXX_INSTALL_INCLUDE_DIR}/${dir}
+      DESTINATION "${LIBCXX_INSTALL_INCLUDE_DIR}/${dir}"
       COMPONENT cxx-headers
       PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
     )
@@ -247,7 +247,7 @@
 
   # Install the generated __config_site.
   install(FILES ${LIBCXX_GENERATED_INCLUDE_TARGET_DIR}/__config_site
-    DESTINATION ${LIBCXX_INSTALL_INCLUDE_TARGET_DIR}
+    DESTINATION "${LIBCXX_INSTALL_INCLUDE_TARGET_DIR}"
     PERMISSIONS OWNER_READ OWNER_WRITE GROUP_READ WORLD_READ
     COMPONENT cxx-headers)
 
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -368,21 +368,21 @@
   install(TARGETS cxx_shared
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT cxx)
 endif()
 
 if (LIBCXX_INSTALL_STATIC_LIBRARY)
   install(TARGETS cxx_static
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT cxx)
 endif()
 
 if(LIBCXX_INSTALL_EXPERIMENTAL_LIBRARY)
   install(TARGETS cxx_experimental
     LIBRARY DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
     ARCHIVE DESTINATION ${LIBCXX_INSTALL_LIBRARY_DIR} COMPONENT cxx
-    RUNTIME DESTINATION bin COMPONENT cxx)
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT cxx)
 endif()
 
 # NOTE: This install command must go after the cxx install command otherwise
diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -26,7 +26,11 @@
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXXABI_STANDALONE_BUILD)
   project(libcxxabi CXX C)
+endif()
+
+include(GNUInstallDirs)
 
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBCXXABI_STANDALONE_BUILD)
   set(PACKAGE_NAME libcxxabi)
   set(PACKAGE_VERSION 11.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -22,7 +22,11 @@
 
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
   project(libunwind LANGUAGES C CXX ASM)
+endif()
+
+include(GNUInstallDirs)
 
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
   set(PACKAGE_NAME libunwind)
   set(PACKAGE_VERSION 13.0.0git)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
diff --git a/libunwind/src/CMakeLists.txt b/libunwind/src/CMakeLists.txt
--- a/libunwind/src/CMakeLists.txt
+++ b/libunwind/src/CMakeLists.txt
@@ -184,7 +184,7 @@
   install(TARGETS ${LIBUNWIND_INSTALL_TARGETS}
     LIBRARY DESTINATION ${LIBUNWIND_INSTALL_LIBRARY_DIR} COMPONENT unwind
     ARCHIVE DESTINATION ${LIBUNWIND_INSTALL_LIBRARY_DIR} COMPONENT unwind
-    RUNTIME DESTINATION bin COMPONENT unwind)
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT unwind)
 endif()
 
 if (NOT CMAKE_CONFIGURATION_TYPES AND LIBUNWIND_INSTALL_LIBRARY)
diff --git a/lld/CMakeLists.txt b/lld/CMakeLists.txt
--- a/lld/CMakeLists.txt
+++ b/lld/CMakeLists.txt
@@ -1,4 +1,10 @@
 # Check if lld is built as a standalone project.
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  project(lld)
+endif()
+
+include(GNUInstallDirs)
+
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lld)
   cmake_minimum_required(VERSION 3.13.4)
@@ -183,7 +189,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     FILES_MATCHING
     PATTERN "*.h"
     )
diff --git a/lld/cmake/modules/AddLLD.cmake b/lld/cmake/modules/AddLLD.cmake
--- a/lld/cmake/modules/AddLLD.cmake
+++ b/lld/cmake/modules/AddLLD.cmake
@@ -22,7 +22,7 @@
       ${export_to_lldtargets}
       LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
       ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-      RUNTIME DESTINATION bin)
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
     if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
       add_llvm_install_targets(install-${name}
@@ -54,7 +54,7 @@
 
     install(TARGETS ${name}
       ${export_to_lldtargets}
-      RUNTIME DESTINATION bin
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
       COMPONENT ${name})
 
     if(NOT CMAKE_CONFIGURATION_TYPES)
diff --git a/lld/tools/lld/CMakeLists.txt b/lld/tools/lld/CMakeLists.txt
--- a/lld/tools/lld/CMakeLists.txt
+++ b/lld/tools/lld/CMakeLists.txt
@@ -25,7 +25,7 @@
 endif()
 
 install(TARGETS lld
-  RUNTIME DESTINATION bin)
+  RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
 if(NOT LLD_SYMLINKS_TO_CREATE)
   set(LLD_SYMLINKS_TO_CREATE
diff --git a/lldb/CMakeLists.txt b/lldb/CMakeLists.txt
--- a/lldb/CMakeLists.txt
+++ b/lldb/CMakeLists.txt
@@ -11,6 +11,11 @@
 # using LLVM as an external library.
 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lldb)
+endif()
+
+include(GNUInstallDirs)
+
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   include(LLDBStandalone)
 
   set(CMAKE_CXX_STANDARD 14 CACHE STRING "C++ standard to conform to")
diff --git a/lldb/cmake/modules/AddLLDB.cmake b/lldb/cmake/modules/AddLLDB.cmake
--- a/lldb/cmake/modules/AddLLDB.cmake
+++ b/lldb/cmake/modules/AddLLDB.cmake
@@ -113,7 +113,7 @@
     endif()
     # RUNTIME is relevant for DLL platforms, FRAMEWORK for macOS
     install(TARGETS ${name} COMPONENT ${name}
-      RUNTIME DESTINATION bin
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
       LIBRARY DESTINATION ${install_dest}
       ARCHIVE DESTINATION ${install_dest}
       FRAMEWORK DESTINATION ${install_dest})
diff --git a/lldb/cmake/modules/LLDBConfig.cmake b/lldb/cmake/modules/LLDBConfig.cmake
--- a/lldb/cmake/modules/LLDBConfig.cmake
+++ b/lldb/cmake/modules/LLDBConfig.cmake
@@ -225,7 +225,7 @@
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/
     COMPONENT lldb-headers
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     FILES_MATCHING
     PATTERN "*.h"
     PATTERN ".cmake" EXCLUDE
@@ -233,7 +233,7 @@
 
   install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/include/
     COMPONENT lldb-headers
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     FILES_MATCHING
     PATTERN "*.h"
     PATTERN ".cmake" EXCLUDE
diff --git a/mlir/CMakeLists.txt b/mlir/CMakeLists.txt
--- a/mlir/CMakeLists.txt
+++ b/mlir/CMakeLists.txt
@@ -4,7 +4,11 @@
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(mlir)
   cmake_minimum_required(VERSION 3.13.4)
+endif()
+
+include(GNUInstallDirs)
 
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
   include(HandleLLVMOptions)
@@ -158,7 +162,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/mlir include/mlir-c
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT mlir-headers
     FILES_MATCHING
     PATTERN "*.def"
@@ -169,7 +173,7 @@
     )
 
   install(DIRECTORY ${MLIR_INCLUDE_DIR}/mlir ${MLIR_INCLUDE_DIR}/mlir-c
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT mlir-headers
     FILES_MATCHING
     PATTERN "*.def"
diff --git a/mlir/cmake/modules/AddMLIR.cmake b/mlir/cmake/modules/AddMLIR.cmake
--- a/mlir/cmake/modules/AddMLIR.cmake
+++ b/mlir/cmake/modules/AddMLIR.cmake
@@ -154,7 +154,7 @@
     ${export_to_mlirtargets}
     LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
     ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
-    RUNTIME DESTINATION bin)
+    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
 
   if (NOT LLVM_ENABLE_IDE)
     add_llvm_install_targets(install-${name}
diff --git a/openmp/CMakeLists.txt b/openmp/CMakeLists.txt
--- a/openmp/CMakeLists.txt
+++ b/openmp/CMakeLists.txt
@@ -7,7 +7,11 @@
 if (OPENMP_STANDALONE_BUILD OR "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   set(OPENMP_STANDALONE_BUILD TRUE)
   project(openmp C CXX)
+endif()
+
+include(GNUInstallDirs)
 
+if (OPENMP_STANDALONE_BUILD OR "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
   # CMAKE_BUILD_TYPE was not set, default to Release.
   if (NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Release)
diff --git a/openmp/runtime/src/CMakeLists.txt b/openmp/runtime/src/CMakeLists.txt
--- a/openmp/runtime/src/CMakeLists.txt
+++ b/openmp/runtime/src/CMakeLists.txt
@@ -311,7 +311,7 @@
   set(LIBOMP_HEADERS_INSTALL_PATH "${OPENMP_INSTALL_LIBDIR}/clang/${CLANG_VERSION}/include")
 endif()
 if(WIN32)
-  install(TARGETS omp RUNTIME DESTINATION bin)
+  install(TARGETS omp RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}")
   install(TARGETS ${LIBOMP_IMP_LIB_TARGET} ARCHIVE DESTINATION "${OPENMP_INSTALL_LIBDIR}")
   # Create aliases (regular copies) of the library for backwards compatibility
   set(LIBOMP_ALIASES "libiomp5md")
diff --git a/openmp/tools/multiplex/CMakeLists.txt b/openmp/tools/multiplex/CMakeLists.txt
--- a/openmp/tools/multiplex/CMakeLists.txt
+++ b/openmp/tools/multiplex/CMakeLists.txt
@@ -4,7 +4,7 @@
   add_library(ompt-multiplex INTERFACE)
   target_include_directories(ompt-multiplex INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 
-  install(FILES ompt-multiplex.h DESTINATION include)
+  install(FILES ompt-multiplex.h DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 
   add_subdirectory(tests)
 endif()
diff --git a/polly/CMakeLists.txt b/polly/CMakeLists.txt
--- a/polly/CMakeLists.txt
+++ b/polly/CMakeLists.txt
@@ -2,7 +2,11 @@
 if (NOT DEFINED LLVM_MAIN_SRC_DIR)
   project(Polly)
   cmake_minimum_required(VERSION 3.13.4)
+endif()
+
+include(GNUInstallDirs)
 
+if (NOT DEFINED LLVM_MAIN_SRC_DIR)
   # Where is LLVM installed?
   find_package(LLVM CONFIG REQUIRED)
   set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${LLVM_CMAKE_DIR})
@@ -122,13 +126,13 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     FILES_MATCHING
     PATTERN "*.h"
     )
 
   install(DIRECTORY ${POLLY_BINARY_DIR}/include/
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     FILES_MATCHING
     PATTERN "*.h"
     PATTERN "CMakeFiles" EXCLUDE
diff --git a/polly/cmake/CMakeLists.txt b/polly/cmake/CMakeLists.txt
--- a/polly/cmake/CMakeLists.txt
+++ b/polly/cmake/CMakeLists.txt
@@ -83,14 +83,15 @@
 set(POLLY_CONFIG_LLVM_CMAKE_DIR "${LLVM_BINARY_DIR}/${LLVM_INSTALL_PACKAGE_DIR}")
 set(POLLY_CONFIG_CMAKE_DIR "${POLLY_INSTALL_PREFIX}/${POLLY_INSTALL_PACKAGE_DIR}")
 set(POLLY_CONFIG_LIBRARY_DIRS "${POLLY_INSTALL_PREFIX}/lib${LLVM_LIBDIR_SUFFIX}")
+get_filename_component(base_includedir "${CMAKE_INSTALL_INCLUDEDIR}" ABSOLUTE BASE_DIR "${POLLY_INSTALL_PREFIX}")
 if (POLLY_BUNDLED_ISL)
   set(POLLY_CONFIG_INCLUDE_DIRS
-    "${POLLY_INSTALL_PREFIX}/include"
-    "${POLLY_INSTALL_PREFIX}/include/polly"
+    "${base_includedir}"
+    "${base_includedir}/polly"
     )
 else()
   set(POLLY_CONFIG_INCLUDE_DIRS
-    "${POLLY_INSTALL_PREFIX}/include"
+    "${base_includedir}"
     ${ISL_INCLUDE_DIRS}
     )
 endif()
@@ -100,12 +101,12 @@
 foreach(tgt IN LISTS POLLY_CONFIG_EXPORTED_TARGETS)
   get_target_property(tgt_type ${tgt} TYPE)
   if (tgt_type STREQUAL "EXECUTABLE")
-    set(tgt_prefix "bin/")
+    set(tgt_prefix "${CMAKE_INSTALL_FULL_BINDIR}/")
   else()
-    set(tgt_prefix "lib/")
+    set(tgt_prefix "${CMAKE_INSTALL_FULL_LIBDIR}/")
   endif()
 
-  set(tgt_path "${CMAKE_INSTALL_PREFIX}/${tgt_prefix}$<TARGET_FILE_NAME:${tgt}>")
+  set(tgt_path "${tgt_prefix}$<TARGET_FILE_NAME:${tgt}>")
   file(RELATIVE_PATH tgt_path ${POLLY_CONFIG_CMAKE_DIR} ${tgt_path})
 
   if (NOT tgt_type STREQUAL "INTERFACE_LIBRARY")
diff --git a/polly/lib/External/CMakeLists.txt b/polly/lib/External/CMakeLists.txt
--- a/polly/lib/External/CMakeLists.txt
+++ b/polly/lib/External/CMakeLists.txt
@@ -290,7 +290,7 @@
     install(DIRECTORY
       ${ISL_SOURCE_DIR}/include/
       ${ISL_BINARY_DIR}/include/
-      DESTINATION include/polly
+      DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/polly"
       FILES_MATCHING
       PATTERN "*.h"
       PATTERN "CMakeFiles" EXCLUDE
diff --git a/pstl/CMakeLists.txt b/pstl/CMakeLists.txt
--- a/pstl/CMakeLists.txt
+++ b/pstl/CMakeLists.txt
@@ -7,6 +7,8 @@
 #===----------------------------------------------------------------------===##
 cmake_minimum_required(VERSION 3.13.4)
 
+include(GNUInstallDirs)
+
 set(PARALLELSTL_VERSION_FILE "${CMAKE_CURRENT_SOURCE_DIR}/include/pstl/internal/pstl_config.h")
 file(STRINGS "${PARALLELSTL_VERSION_FILE}" PARALLELSTL_VERSION_SOURCE REGEX "#define _PSTL_VERSION .*$")
 string(REGEX REPLACE "#define _PSTL_VERSION (.*)$" "\\1" PARALLELSTL_VERSION_SOURCE "${PARALLELSTL_VERSION_SOURCE}")
@@ -86,10 +88,10 @@
               "${CMAKE_CURRENT_BINARY_DIR}/ParallelSTLConfigVersion.cmake"
         DESTINATION lib/cmake/ParallelSTL)
 install(DIRECTORY include/
-        DESTINATION include
+        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
         PATTERN "*.in" EXCLUDE)
 install(FILES "${PSTL_CONFIG_SITE_PATH}"
-        DESTINATION include)
+        DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}")
 
 add_custom_target(install-pstl
                   COMMAND "${CMAKE_COMMAND}" -P "${PROJECT_BINARY_DIR}/cmake_install.cmake" -DCOMPONENT=ParallelSTL)