diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -2,6 +2,8 @@
 
 cmake_minimum_required(VERSION 3.13.4)
 
+include(GNUInstallDirs)
+
 # CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
 # New in CMake 3.20. https://cmake.org/cmake/help/latest/policy/CMP0116.html
 if(POLICY CMP0116)
@@ -70,7 +72,7 @@
 # List of all known projects in the mono repo
 set(LLVM_KNOWN_PROJECTS "${LLVM_ALL_PROJECTS};${LLVM_EXTRA_PROJECTS}")
 set(LLVM_ENABLE_PROJECTS "" CACHE STRING
-	"Semicolon-separated list of projects to build (${LLVM_KNOWN_PROJECTS}), or \"all\".")
+   "Semicolon-separated list of projects to build (${LLVM_KNOWN_PROJECTS}), or \"all\".")
 foreach(proj ${LLVM_ENABLE_PROJECTS})
   if (NOT proj STREQUAL "all" AND NOT proj STREQUAL "llvm" AND NOT "${proj}" IN_LIST LLVM_KNOWN_PROJECTS)
      MESSAGE(FATAL_ERROR "${proj} isn't a known project: ${LLVM_KNOWN_PROJECTS}")
@@ -159,7 +161,7 @@
   find_program(CCACHE_PROGRAM ccache)
   if(CCACHE_PROGRAM)
       set(LLVM_CCACHE_MAXSIZE "" CACHE STRING "Size of ccache")
-      set(LLVM_CCACHE_DIR "" CACHE STRING "Directory to keep ccached data")
+      set(LLVM_CCACHE_DIR "" CACHE PATH "Directory to keep ccached data")
       set(LLVM_CCACHE_PARAMS "CCACHE_CPP2=yes CCACHE_HASHDIR=yes"
           CACHE STRING "Parameters to pass through to ccache")
 
@@ -197,10 +199,10 @@
 endif()
 
 # Add path for custom modules
-set(CMAKE_MODULE_PATH
-  ${CMAKE_MODULE_PATH}
+list(INSERT CMAKE_MODULE_PATH 0
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake"
   "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules"
+  "${CMAKE_CURRENT_SOURCE_DIR}/../cmake/Modules"
   )
 
 # Generate a CompilationDatabase (compile_commands.json file) for our build,
@@ -283,13 +285,18 @@
 
 set(LLVM_LIBDIR_SUFFIX "" CACHE STRING "Define suffix of library directory name (32/64)" )
 
-set(LLVM_TOOLS_INSTALL_DIR "bin" CACHE STRING "Path for binary subdirectory (defaults to 'bin')")
+set(LLVM_TOOLS_INSTALL_DIR "${CMAKE_INSTALL_BINDIR}" CACHE PATH
+    "Path for binary subdirectory (defaults to '${CMAKE_INSTALL_BINDIR}')")
 mark_as_advanced(LLVM_TOOLS_INSTALL_DIR)
 
-set(LLVM_UTILS_INSTALL_DIR "${LLVM_TOOLS_INSTALL_DIR}" CACHE STRING
+set(LLVM_UTILS_INSTALL_DIR "${LLVM_TOOLS_INSTALL_DIR}" CACHE PATH
     "Path to install LLVM utilities (enabled by LLVM_INSTALL_UTILS=ON) (defaults to LLVM_TOOLS_INSTALL_DIR)")
 mark_as_advanced(LLVM_UTILS_INSTALL_DIR)
 
+set(LLVM_EXAMPLES_INSTALL_DIR "examples" CACHE PATH
+    "Path for examples subdirectory (enabled by LLVM_BUILD_EXAMPLES=ON) (defaults to 'examples')")
+mark_as_advanced(LLVM_EXAMPLES_INSTALL_DIR)
+
 # They are used as destination of target generators.
 set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
 set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
@@ -343,7 +350,7 @@
     CACHE STRING "Semicolon-separated list of targets to build, or \"all\".")
 
 set(LLVM_EXPERIMENTAL_TARGETS_TO_BUILD ""
-  CACHE STRING "Semicolon-separated list of experimental targets to build.")
+    CACHE STRING "Semicolon-separated list of experimental targets to build.")
 
 option(BUILD_SHARED_LIBS
   "Build all libraries as shared libraries instead of static" OFF)
@@ -396,7 +403,7 @@
 
 set(LLVM_ENABLE_CURL "OFF" CACHE STRING "Use libcurl for the HTTP client if available. Can be ON, OFF, or FORCE_ON")
 
-set(LLVM_Z3_INSTALL_DIR "" CACHE STRING "Install directory of the Z3 solver.")
+set(LLVM_Z3_INSTALL_DIR "" CACHE PATH "Install directory of the Z3 solver.")
 
 option(LLVM_ENABLE_Z3_SOLVER
   "Enable Support for the Z3 constraint solver in LLVM."
@@ -605,10 +612,10 @@
 option (LLVM_ENABLE_OCAMLDOC "Build OCaml bindings documentation." ON)
 option (LLVM_ENABLE_BINDINGS "Build bindings." ON)
 
-set(LLVM_INSTALL_DOXYGEN_HTML_DIR "share/doc/llvm/doxygen-html"
-    CACHE STRING "Doxygen-generated HTML documentation install directory")
-set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "share/doc/llvm/ocaml-html"
-    CACHE STRING "OCamldoc-generated HTML documentation install directory")
+set(LLVM_INSTALL_DOXYGEN_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/llvm/doxygen-html"
+    CACHE PATH "Doxygen-generated HTML documentation install directory")
+set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/llvm/ocaml-html"
+    CACHE PATH "OCamldoc-generated HTML documentation install directory")
 
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
@@ -1122,7 +1129,7 @@
 
 if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
   install(DIRECTORY include/llvm include/llvm-c
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT llvm-headers
     FILES_MATCHING
     PATTERN "*.def"
@@ -1133,7 +1140,7 @@
     )
 
   install(DIRECTORY ${LLVM_INCLUDE_DIR}/llvm ${LLVM_INCLUDE_DIR}/llvm-c
-    DESTINATION include
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
     COMPONENT llvm-headers
     FILES_MATCHING
     PATTERN "*.def"
@@ -1147,13 +1154,13 @@
 
   if (LLVM_INSTALL_MODULEMAPS)
     install(DIRECTORY include/llvm include/llvm-c
-            DESTINATION include
+            DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
             COMPONENT llvm-headers
             FILES_MATCHING
             PATTERN "module.modulemap"
             )
     install(FILES include/llvm/module.install.modulemap
-            DESTINATION include/llvm
+            DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/llvm"
             COMPONENT llvm-headers
             RENAME "module.extern.modulemap"
             )
diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1,3 +1,4 @@
+include(GNUInstallDirs)
 include(LLVMDistributionSupport)
 include(LLVMProcessSources)
 include(LLVM-Config)
@@ -837,7 +838,7 @@
               ${export_to_llvmexports}
               LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
               ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT ${name}
-              RUNTIME DESTINATION bin COMPONENT ${name})
+              RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}" COMPONENT ${name})
 
       if (NOT LLVM_ENABLE_IDE)
         add_llvm_install_targets(install-${name}
@@ -1270,7 +1271,7 @@
   endif()
   add_llvm_executable(${name} ${ARGN})
   if( LLVM_BUILD_EXAMPLES )
-    install(TARGETS ${name} RUNTIME DESTINATION examples)
+    install(TARGETS ${name} RUNTIME DESTINATION "${LLVM_EXAMPLES_INSTALL_DIR}")
   endif()
   set_target_properties(${name} PROPERTIES FOLDER "Examples")
 endmacro(add_llvm_example name)
diff --git a/llvm/cmake/modules/AddSphinxTarget.cmake b/llvm/cmake/modules/AddSphinxTarget.cmake
--- a/llvm/cmake/modules/AddSphinxTarget.cmake
+++ b/llvm/cmake/modules/AddSphinxTarget.cmake
@@ -86,8 +86,8 @@
         endif()
       elseif (builder STREQUAL html)
         string(TOUPPER "${project}" project_upper)
-        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "share/doc/${project}/html"
-            CACHE STRING "HTML documentation install directory for ${project}")
+        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/html"
+            CACHE PATH "HTML documentation install directory for ${project}")
 
         # '/.' indicates: copy the contents of the directory directly into
         # the specified destination, without recreating the last component
diff --git a/llvm/cmake/modules/CMakeLists.txt b/llvm/cmake/modules/CMakeLists.txt
--- a/llvm/cmake/modules/CMakeLists.txt
+++ b/llvm/cmake/modules/CMakeLists.txt
@@ -1,3 +1,4 @@
+include(ExtendPath)
 include(LLVMDistributionSupport)
 
 set(LLVM_INSTALL_PACKAGE_DIR lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm)
@@ -96,24 +97,37 @@
   PATTERN CMakeFiles EXCLUDE
   )
 
+#
 # Generate LLVMConfig.cmake for the install tree.
-set(LLVM_CONFIG_CODE "
-# Compute the installation prefix from this LLVMConfig.cmake file location.
-get_filename_component(LLVM_INSTALL_PREFIX \"\${CMAKE_CURRENT_LIST_FILE}\" PATH)")
-# Construct the proper number of get_filename_component(... PATH)
-# calls to compute the installation prefix.
-string(REGEX REPLACE "/" ";" _count "${LLVM_INSTALL_PACKAGE_DIR}")
-foreach(p ${_count})
-  set(LLVM_CONFIG_CODE "${LLVM_CONFIG_CODE}
-get_filename_component(LLVM_INSTALL_PREFIX \"\${LLVM_INSTALL_PREFIX}\" PATH)")
-endforeach(p)
-set(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}/include")
+#
+
+# Find common prefix if relative path, CMAKE_INSTALL_PREFIX if absolute
+if(IS_ABSOLUTE "${LLVM_INSTALL_PACKAGE_DIR}")
+  set(LLVM_CONFIG_CODE
+    "# Installation prefix is fixed absolute path"
+    "set(LLVM_INSTALL_PREFIX \"${CMAKE_INSTALL_PREFIX}\"")
+else()
+  set(LLVM_CONFIG_CODE
+    "# Compute the installation prefix from this LLVMConfig.cmake file location."
+    "get_filename_component(LLVM_INSTALL_PREFIX \"\${CMAKE_CURRENT_LIST_FILE}\" PATH)")
+  # Construct the proper number of get_filename_component(... PATH)
+  # calls to compute the installation prefix.
+  string(REGEX REPLACE "/" ";" _count "${LLVM_INSTALL_PACKAGE_DIR}")
+  foreach(p ${_count})
+    list(APPEND LLVM_CONFIG_CODE
+      "get_filename_component(LLVM_INSTALL_PREFIX \"\${LLVM_INSTALL_PREFIX}\" PATH)")
+  endforeach(p)
+endif()
+string(REPLACE ";" "\n" LLVM_CONFIG_CODE "${LLVM_CONFIG_CODE}")
+
+# Set path variables for config file
+extend_path(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}" "${CMAKE_INSTALL_INCLUDEDIR}")
 set(LLVM_CONFIG_INCLUDE_DIR "${LLVM_CONFIG_INCLUDE_DIRS}")
 set(LLVM_CONFIG_MAIN_INCLUDE_DIR "${LLVM_CONFIG_INCLUDE_DIRS}")
 set(LLVM_CONFIG_BINARY_DIR "\${LLVM_INSTALL_PREFIX}")
-set(LLVM_CONFIG_CMAKE_DIR "\${LLVM_INSTALL_PREFIX}/${LLVM_INSTALL_PACKAGE_DIR}")
-set(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}/bin")
-set(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}/lib\${LLVM_LIBDIR_SUFFIX}")
+extend_path(LLVM_CONFIG_CMAKE_DIR "\${LLVM_INSTALL_PREFIX}" "${LLVM_INSTALL_PACKAGE_DIR}")
+extend_path(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}" "${LLVM_TOOLS_INSTALL_DIR}")
+extend_path(LLVM_CONFIG_LIBRARY_DIR "\${LLVM_INSTALL_PREFIX}" "lib\${LLVM_LIBDIR_SUFFIX}")
 
 # Generate a default location for lit
 if (LLVM_INSTALL_UTILS AND LLVM_BUILD_UTILS)
diff --git a/llvm/cmake/modules/LLVMInstallSymlink.cmake b/llvm/cmake/modules/LLVMInstallSymlink.cmake
--- a/llvm/cmake/modules/LLVMInstallSymlink.cmake
+++ b/llvm/cmake/modules/LLVMInstallSymlink.cmake
@@ -2,9 +2,11 @@
 # DESTDIR environment variable may be unset at configuration time.
 # See PR8397.
 
+include(GNUInstallDirs)
+
 function(install_symlink name target outdir)
   set(DESTDIR $ENV{DESTDIR})
-  set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/${outdir}/")
+  set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/${outdir}")
 
   message(STATUS "Creating ${name}")
 
diff --git a/llvm/docs/CMake.rst b/llvm/docs/CMake.rst
--- a/llvm/docs/CMake.rst
+++ b/llvm/docs/CMake.rst
@@ -252,6 +252,22 @@
   Sets the C++ standard to conform to when building LLVM.  Possible values are
   14, 17, 20.  LLVM Requires C++ 14 or higher.  This defaults to 14.
 
+**CMAKE_INSTALL_BINDIR**:PATH
+  The path to install executables, relative to the *CMAKE_INSTALL_PREFIX*.
+  Defaults to "bin".
+
+**CMAKE_INSTALL_INCLUDEDIR**:PATH
+  The path to install header files, relative to the *CMAKE_INSTALL_PREFIX*.
+  Defaults to "include".
+
+**CMAKE_INSTALL_DOCDIR**:PATH
+  The path to install documentation, relative to the *CMAKE_INSTALL_PREFIX*.
+  Defaults to "share/doc".
+
+**CMAKE_INSTALL_MANDIR**:PATH
+  The path to install manpage files, relative to the *CMAKE_INSTALL_PREFIX*.
+  Defaults to "share/man".
+
 .. _LLVM-related variables:
 
 LLVM-related variables
@@ -595,15 +611,15 @@
   Install symliks from the cctools tool names to the corresponding LLVM tools.
   For example, lipo will be symlinked to llvm-lipo.
 
-**LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
+**LLVM_INSTALL_OCAMLDOC_HTML_DIR**:PATH
   The path to install OCamldoc-generated HTML documentation to. This path can
   either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
-  `share/doc/llvm/ocaml-html`.
+  ``${CMAKE_INSTALL_DOCDIR}/llvm/ocaml-html``.
 
-**LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
+**LLVM_INSTALL_SPHINX_HTML_DIR**:PATH
   The path to install Sphinx-generated HTML documentation to. This path can
   either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
-  `share/doc/llvm/html`.
+  ``${CMAKE_INSTALL_DOCDIR}/llvm/html``.
 
 **LLVM_INSTALL_UTILS**:BOOL
   If enabled, utility binaries like ``FileCheck`` and ``not`` will be installed
@@ -627,8 +643,8 @@
 
 **LLVM_INSTALL_DOXYGEN_HTML_DIR**:STRING
   The path to install Doxygen-generated HTML documentation to. This path can
-  either be absolute or relative to the CMAKE_INSTALL_PREFIX. Defaults to
-  `share/doc/llvm/doxygen-html`.
+  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
+  ``${CMAKE_INSTALL_DOCDIR}/llvm/doxygen-html``.
 
 **LLVM_LINK_LLVM_DYLIB**:BOOL
   If enabled, tools will be linked with the libLLVM shared library. Defaults
@@ -764,6 +780,26 @@
   If enabled then sphinx documentation warnings will be treated as
   errors. Defaults to ON.
 
+Advanced variables
+~~~~~~~~~~~~~~~~~~
+
+These are niche, and changing them from their defaults is more likely to cause
+things to go wrong.  They are also unstable across LLVM versions.
+
+**LLVM_TOOLS_INSTALL_DIR**:PATH
+  The path to install the main LLVM tools, relative to the *CMAKE_INSTALL_PREFIX*.
+  Defaults to *CMAKE_INSTALL_BINDIR*.
+
+**LLVM_UTILS_INSTALL_DIR**:PATH
+  The path to install auxiliary LLVM utilities, relative to the *CMAKE_INSTALL_PREFIX*.
+  Only matters if *LLVM_INSTALL_UTILS* is enabled.
+  Defaults to *LLVM_TOOLS_INSTALL_DIR*.
+
+**LLVM_EXAMPLES_INSTALL_DIR**:PATH
+  The path for examples of using LLVM, relative to the *CMAKE_INSTALL_PREFIX*.
+  Only matters if *LLVM_BUILD_EXAMPLES* is enabled.
+  Defaults to "examples".
+
 CMake Caches
 ============
 
diff --git a/llvm/examples/Bye/CMakeLists.txt b/llvm/examples/Bye/CMakeLists.txt
--- a/llvm/examples/Bye/CMakeLists.txt
+++ b/llvm/examples/Bye/CMakeLists.txt
@@ -14,6 +14,6 @@
     BUILDTREE_ONLY
    )
 
-  install(TARGETS ${name} RUNTIME DESTINATION examples)
+  install(TARGETS ${name} RUNTIME DESTINATION "${LLVM_EXAMPLES_INSTALL_DIR}")
   set_target_properties(${name} PROPERTIES FOLDER "Examples")
 endif()
diff --git a/llvm/tools/llvm-config/BuildVariables.inc.in b/llvm/tools/llvm-config/BuildVariables.inc.in
--- a/llvm/tools/llvm-config/BuildVariables.inc.in
+++ b/llvm/tools/llvm-config/BuildVariables.inc.in
@@ -23,6 +23,7 @@
 #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
 #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
 #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
+#define LLVM_INSTALL_INCLUDEDIR "@CMAKE_INSTALL_INCLUDEDIR@"
 #define LLVM_TARGETS_BUILT "@LLVM_TARGETS_BUILT@"
 #define LLVM_SYSTEM_LIBS "@LLVM_SYSTEM_LIBS@"
 #define LLVM_BUILD_SYSTEM "@LLVM_BUILD_SYSTEM@"
diff --git a/llvm/tools/llvm-config/llvm-config.cpp b/llvm/tools/llvm-config/llvm-config.cpp
--- a/llvm/tools/llvm-config/llvm-config.cpp
+++ b/llvm/tools/llvm-config/llvm-config.cpp
@@ -357,10 +357,16 @@
         ("-I" + ActiveIncludeDir + " " + "-I" + ActiveObjRoot + "/include");
   } else {
     ActivePrefix = CurrentExecPrefix;
-    ActiveIncludeDir = ActivePrefix + "/include";
-    SmallString<256> path(LLVM_TOOLS_INSTALL_DIR);
-    sys::fs::make_absolute(ActivePrefix, path);
-    ActiveBinDir = std::string(path.str());
+    {
+      SmallString<256> Path(LLVM_INSTALL_INCLUDEDIR);
+      sys::fs::make_absolute(ActivePrefix, Path);
+      ActiveIncludeDir = std::string(Path.str());
+    }
+    {
+      SmallString<256> Path(LLVM_TOOLS_INSTALL_DIR);
+      sys::fs::make_absolute(ActivePrefix, Path);
+      ActiveBinDir = std::string(Path.str());
+    }
     ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
     ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
     ActiveIncludeOption = "-I" + ActiveIncludeDir;
diff --git a/llvm/tools/lto/CMakeLists.txt b/llvm/tools/lto/CMakeLists.txt
--- a/llvm/tools/lto/CMakeLists.txt
+++ b/llvm/tools/lto/CMakeLists.txt
@@ -33,7 +33,7 @@
     ${SOURCES} DEPENDS intrinsics_gen)
 
 install(FILES ${LLVM_MAIN_INCLUDE_DIR}/llvm-c/lto.h
-  DESTINATION include/llvm-c
+  DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/llvm-c"
   COMPONENT LTO)
 
 if (APPLE)
diff --git a/llvm/tools/opt-viewer/CMakeLists.txt b/llvm/tools/opt-viewer/CMakeLists.txt
--- a/llvm/tools/opt-viewer/CMakeLists.txt
+++ b/llvm/tools/opt-viewer/CMakeLists.txt
@@ -8,7 +8,7 @@
 
 foreach (file ${files})
   install(PROGRAMS ${file}
-    DESTINATION share/opt-viewer
+    DESTINATION "${CMAKE_INSTALL_DATADIR}/opt-viewer"
     COMPONENT opt-viewer)
 endforeach (file)
 
diff --git a/llvm/tools/remarks-shlib/CMakeLists.txt b/llvm/tools/remarks-shlib/CMakeLists.txt
--- a/llvm/tools/remarks-shlib/CMakeLists.txt
+++ b/llvm/tools/remarks-shlib/CMakeLists.txt
@@ -19,7 +19,7 @@
   endif()
   
   install(FILES ${LLVM_MAIN_INCLUDE_DIR}/llvm-c/Remarks.h
-    DESTINATION include/llvm-c
+    DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/llvm-c"
     COMPONENT Remarks)
 
   if (APPLE)