Support for custom install dirs in CMake build

[nalimilan]

Summary

This restores support for custom install directories, which was lost when moving from autotools to CMake. This is needed in particular by distributions to build versioned LLVM packages which are parallel-installable with the latest version.

This introduces new CMAKE_INSTALL_* variables, following the naming convention used by the GNUInstallDirs CMake module: for BINDIR, LIBDIR, INCLUDEDIR, DOCDIR and MANDIR. Existing variables are preserved, and take their defaults from or determine the new ones' defaults as appropriate.

[beanz]

I think this patch is mostly going in the right direction, and I'm actually very happy to see this functionality coming in.

I have a bunch of inline comments below.

CMakeLists.txt

299

In keeping with our conventions these variables probably should start with LLVM instead of CMAKE.

301

Generally speaking having a CMake cache variable that is derived from the value of another cache variable is really bad. If you update LLVM_LIBDIR_SUFFIX in this case CMAKE_INSTALL_LIBDIR will not be updated.

305

This is also bad for similar reasons as above.

310

Again, don't set cached variables off other cached variables.

312

Here too.

tools/llvm-config/BuildVariables.inc.in

26

Maybe rather than LLVM_BINARY_DIR here you keep the INSTALL_BINDIR name. LLVM_BINARY_DIR has a very specific meaning elsewhere in our build system.

The same is true for LLVM_LIBRARY_DIR and LLVM_INCLUDE_DIR, so it is probably best to use the INSTALL_* names there too.

[beanz]

Adding LLVM-commits since it was left off.

[mgorny]

CMakeLists.txt

299

And anyway, why were you reinventing GNUInstallDirs? If we want the CMAKE* vars, I don't see a reason not to use the module completely.

[nalimilan]

Thanks for the review!

CMakeLists.txt

299

I'm not that familiar with CMake, so I don't really know how modules work.I thought I would propose the less invasive patch for a start. But I can use GNUInstallDirs if you think that's the best approach.

301

I see, but what should I do here? Drop LLVM_LIBDIR_SUFFIX? Stop caching it? Same for the other uses, I'm not sure what's the best approach.

305

Is there a reason to use ${project} here instead of just llvm?

[mgorny]

CMakeLists.txt

305

Yes. Those paths were used in e.g. clang, and there project evaluated to clang. At least for stand-alone builds, that is.

[beanz]

CMakeLists.txt

299

If you use the GNUInstallDirs module, then it makes sense to keep the CMAKE_* prefixes, however GNUInstallDirs may not play well with LLVM_LIBDIR_SUFFIX.

301

I would not include LLVM_LIBDIR_SUFFIX in the cached variable and instead include it at the use sites. CMake has no strategy for cache invalidation, so once a variable is cached it is very difficult to make it not cached.

305

I would drop ${project} from the cached variable and have the docs directory add project at the end in each sub-project.

[nalimilan]

Sorry for the delay. I think this new revision takes into account all remarks. Though the naming of the variables is still open for discussion.

[nalimilan]

CMakeLists.txt

299

Yeah, so we cannot use GNUInstallDirs without breaking backward compatibility WRT LLVM_LIBDIR_SUFFIX. So I won't use it unless you're OK with dropping that variable.

Yet I suggest using the same names instead of adding an LLVM suffix: that's more discoverable for users; it doesn't really make sense to change the same of these standard variables for each project. In particular, Linux distributions offer convenience macros to build packages, which cannot work if variables don't follow a standard scheme.

Though e.g. Fedora currently uses a different convention, with LIB_INSTALL_DIR, INCLUDE_INSTALL_DIR and SHARE_INSTALL_PREFIX. I guess we could use that instead.

[beanz]

A few comments inline. Since these variables are used by the LLVM CMake modules, they also need to be added to LLVMConfig.cmake.in. Otherwise they will break out-of-tree builds.

CMakeLists.txt

310

Since this isn't cached, you also shouldn't put a type or comment.

312

This one too.

[nalimilan]

Done.

[nalimilan]

Bump. I have rebased against current master.

[nalimilan]

Re-bump. ;-)

[nalimilan]

Re-re-bump!

[mgorny]

Hmm, what about using GNUInstallDirs, and adding some extra initial logic to handle LLVM_LIBDIR_SUFFIX? I'm wondering how ugly would it be e.g. to detect when ${CMAKE_INSTALL_LIBDIR} ends with ${LLVM_LIBDIR_SUFFIX}, and unset the latter in that case (maybe with an informatory message).

[nalimilan]

Given that the PR works as-is and doesn't add too much code, I don't really see the advantage of moving to an "ugly" solution just to use GNUInstallDirs. Is there a strong advantage to that?

[mgorny]

Are you seriously asking me if there's an advantage to reusing existing, standard, built-in solution that lets users apply the same solutions across different CMake projects over reinventing the wheel, poorly in an unpredictably incompatible way that's going to surprise everyone who knows GNUInstallDirs and sees CMAKE_INSTALL_LIBDIR that behaves differently than the one he knows?

[krytarowski]

In D28234#1337321, @nalimilan wrote:

Given that the PR works as-is and doesn't add too much code, I don't really see the advantage of moving to an "ugly" solution just to use GNUInstallDirs. Is there a strong advantage to that?

Please do use GNUInstallDirs. This way it will be compatible with all cmake users beyond few tested targets and it will be easy to tweak using standard cmake options.

[nalimilan]

Well, I'm all for using standard solutions in general. But I'm afraid GNUInstallDirs won't play very well with LLVM_LIBDIR_SUFFIX. Let me investigate that again (last time you asked me this was almost two years ago...).

[krytarowski]

In D28234#1337338, @nalimilan wrote:

Well, I'm all for using standard solutions in general. But I'm afraid GNUInstallDirs won't play very well with LLVM_LIBDIR_SUFFIX. Let me investigate that again (last time you asked me this was almost two years ago...).

libdir suffix is mostly linux thing and should be handled through GNUInstallDirs.

[Ericson2314]

I am interested in this. Were it to be revived and, say, made to use GNUInstallDirs as others suggest, would this be something that might land?

[lebedev.ri]

In D28234#2532970, @Ericson2314 wrote:

I am interested in this. Were it to be revived and, say, made to use GNUInstallDirs as others suggest, would this be something that might land?

In general - i think so

[Ericson2314]

Rebase to latest main

[Ericson2314]

OK so anyone have any opinions on how GNUInstallDirs ought out to interact with the llvm prefix suffix, and build-mode?

Also, while I did the plain rebase reusing this diff, I suppose I should open a new one for the more creatively-different GNUInstallDirs-using version.

[Ericson2314]

I made a new version of this D99484. I figured a separate revision was in order as I substantially revised it and it now supports many more LLVM projects than just llvm/ proper.

CMakeLists.txt

   message(FATAL_ERROR "Invalid value for CMAKE_BUILD_TYPE: ${CMAKE_BUILD_TYPE}")
 endif()
 
-set(LLVM_LIBDIR_SUFFIX "" CACHE STRING "Define suffix of library directory name (32/64)" )
+set(LLVM_LIBDIR_SUFFIX ""
+    CACHE STRING "Define suffix of library directory name (32/64)" )
+set(CMAKE_INSTALL_BINDIR bin
+    CACHE STRING "Path for binary directory relative to CMAKE_INSTALL_PREFIX (defaults to 'bin')" )
+set(CMAKE_INSTALL_LIBDIR lib
+    CACHE STRING "Path for library directory relative to CMAKE_INSTALL_PREFIX (defaults to 'lib'" )
+set(CMAKE_INSTALL_INCLUDEDIR include
+    CACHE STRING "Path for include directory relative to CMAKE_INSTALL_PREFIX (defaults to 'include'" )
+set(CMAKE_INSTALL_DOCDIR share/doc
+    CACHE STRING "Path for documentation directory relative to CMAKE_INSTALL_PREFIX (defaults to 'share/doc')" )
+set(CMAKE_INSTALL_MANDIR share/man
+    CACHE STRING "Path for manpages directory relative to CMAKE_INSTALL_PREFIX (defaults to 'share/man')" )
 
-set(LLVM_TOOLS_INSTALL_DIR "bin" CACHE STRING "Path for binary subdirectory (defaults to 'bin')")
-mark_as_advanced(LLVM_TOOLS_INSTALL_DIR)
+set(LLVM_INSTALL_DOXYGEN_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/doxygen-html")
+set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/ocaml-html")
 
 set(LLVM_UTILS_INSTALL_DIR "${LLVM_TOOLS_INSTALL_DIR}" CACHE STRING
     "Path to install LLVM utilities (enabled by LLVM_INSTALL_UTILS=ON) (defaults to LLVM_TOOLS_INSTALL_DIR)")

 mark_as_advanced(LLVM_UTILS_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})
+set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/${CMAKE_INSTALL_BINDIR})
+set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
 if(WIN32 OR CYGWIN)
   # DLL platform -- put DLLs into bin.
   set(LLVM_SHLIB_OUTPUT_INTDIR ${LLVM_RUNTIME_OUTPUT_INTDIR})

 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")
-
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
 

 
 
 # They are not referenced. See set_output_directory().
-set( CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/bin )
-set( CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX} )
-set( CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/lib${LLVM_LIBDIR_SUFFIX} )
+set( CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/${CMAKE_INSTALL_BINDIR} )
+set( CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX} )
+set( CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LLVM_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX} )
 
 if(APPLE AND DARWIN_LTO_LIBRARY)
   set(CMAKE_EXE_LINKER_FLAGS

 
 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"

     )
 
   install(DIRECTORY ${LLVM_INCLUDE_DIR}/llvm ${LLVM_INCLUDE_DIR}/llvm-c
-    DESTINATION include
+    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
     COMPONENT llvm-headers
     FILES_MATCHING
     PATTERN "*.def"

cmake/modules/AddLLVM.cmake

   else()
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "LTO" OR
         (LLVM_LINK_LLVM_DYLIB AND ${name} STREQUAL "LLVM"))
-      set(install_dir lib${LLVM_LIBDIR_SUFFIX})
+      set(install_dir ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
       if(ARG_SHARED OR BUILD_SHARED_LIBS)
         if(WIN32 OR CYGWIN OR MINGW)
           set(install_type RUNTIME)

           # DLL platform
           set(dlldir "bin")
         else()
-          set(dlldir "lib${LLVM_LIBDIR_SUFFIX}")
+          set(dlldir "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
         endif()
 
         if(${name} IN_LIST LLVM_DISTRIBUTION_COMPONENTS OR

         install(TARGETS ${name}
                 ${export_to_llvmexports}
                 LIBRARY DESTINATION ${dlldir}
-                ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX})
+                ARCHIVE DESTINATION ${CMAKE_INSTALL_BINDIR})
       endif()
       set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${name})
     endif()

 
       install(TARGETS ${name}
               ${export_to_llvmexports}
-              RUNTIME DESTINATION ${LLVM_TOOLS_INSTALL_DIR}
+              RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
               COMPONENT ${name})
 
       if (NOT CMAKE_CONFIGURATION_TYPES)

   endif()
   add_llvm_executable(${name} ${ARGN})
   if( LLVM_BUILD_EXAMPLES )
-    install(TARGETS ${name} RUNTIME DESTINATION examples)
+    install(TARGETS ${name} RUNTIME DESTINATION ${CMAKE_INSTALL_DOCDIR}/examples)
   endif()
   set_target_properties(${name} PROPERTIES FOLDER "Examples")
 endmacro(add_llvm_example name)

   set_target_properties(${name} PROPERTIES FOLDER "Utils")
   if( LLVM_INSTALL_UTILS AND LLVM_BUILD_UTILS )
     install (TARGETS ${name}
-      RUNTIME DESTINATION ${LLVM_UTILS_INSTALL_DIR}
+      RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
       COMPONENT ${name})
     if (NOT CMAKE_CONFIGURATION_TYPES)
       add_llvm_install_targets(install-${name}

   set(full_name ${CMAKE_${type}_LIBRARY_PREFIX}${name}${CMAKE_${type}_LIBRARY_SUFFIX})
   set(full_dest ${CMAKE_${type}_LIBRARY_PREFIX}${dest}${CMAKE_${type}_LIBRARY_SUFFIX})
 
-  set(output_dir lib${LLVM_LIBDIR_SUFFIX})
+  set(output_dir ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
   if(WIN32 AND "${type}" STREQUAL "SHARED")
     set(output_dir bin)
   endif()

   set(full_dest ${dest}${CMAKE_EXECUTABLE_SUFFIX})
 
   install(SCRIPT ${INSTALL_SYMLINK}
-          CODE "install_symlink(${full_name} ${full_dest} ${LLVM_TOOLS_INSTALL_DIR})"
+          CODE "install_symlink(${full_name} ${full_dest} ${CMAKE_INSTALL_BINDIR})"
           COMPONENT ${component})
 
   if (NOT CMAKE_CONFIGURATION_TYPES AND NOT ARG_ALWAYS_GENERATE)

     set(_install_name_dir INSTALL_NAME_DIR "@rpath")
     set(_install_rpath "@loader_path/../lib" ${extra_libdir})
   elseif(UNIX)
-    set(_install_rpath "\$ORIGIN/../lib${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
+    set(_install_rpath "\$ORIGIN/../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" ${extra_libdir})
     if(${CMAKE_SYSTEM_NAME} MATCHES "(FreeBSD|DragonFly)")
       set_property(TARGET ${name} APPEND_STRING PROPERTY
                    LINK_FLAGS " -Wl,-z,origin ")

cmake/modules/AddOCaml.cmake

   endforeach()
 
   if( APPLE )
-    set(ocaml_rpath "@executable_path/../../../lib${LLVM_LIBDIR_SUFFIX}")
+    set(ocaml_rpath "@executable_path/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
   elseif( UNIX )
-    set(ocaml_rpath "\\$ORIGIN/../../../lib${LLVM_LIBDIR_SUFFIX}")
+    set(ocaml_rpath "\\$ORIGIN/../../../${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
   endif()
   list(APPEND ocaml_flags "-ldopt" "-Wl,-rpath,${ocaml_rpath}")
 

cmake/modules/AddSphinxTarget.cmake

 
       elseif (builder STREQUAL html)
         string(TOUPPER "${project}" project_upper)
-        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "share/doc/${project}/html"
+        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "${CMAKE_INSTALL_DOCDIR}/${project}/html"
             CACHE STRING "HTML documentation install directory for ${project}")
 
         # '/.' indicates: copy the contents of the directory directly into

cmake/modules/CMakeLists.txt

-set(LLVM_INSTALL_PACKAGE_DIR lib${LLVM_LIBDIR_SUFFIX}/cmake/llvm)
+set(LLVM_INSTALL_PACKAGE_DIR ${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/cmake/llvm CACHE STRING "Path for CMake subdirectory (defaults to 'cmake/llvm')")
 set(llvm_cmake_builddir "${LLVM_BINARY_DIR}/${LLVM_INSTALL_PACKAGE_DIR}")
 
 # First for users who use an installed LLVM, create the LLVMExports.cmake file.

   set(LLVM_CONFIG_CODE "${LLVM_CONFIG_CODE}
 get_filename_component(LLVM_INSTALL_PREFIX \"\${LLVM_INSTALL_PREFIX}\" PATH)")
 endforeach(p)
-set(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}/include")
-set(LLVM_CONFIG_LIBRARY_DIRS "\${LLVM_INSTALL_PREFIX}/lib\${LLVM_LIBDIR_SUFFIX}")
+set(LLVM_CONFIG_INCLUDE_DIRS "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_INCLUDEDIR}")
+set(LLVM_CONFIG_LIBRARY_DIRS "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}")
 set(LLVM_CONFIG_CMAKE_DIR "\${LLVM_INSTALL_PREFIX}/${LLVM_INSTALL_PACKAGE_DIR}")
 set(LLVM_CONFIG_BINARY_DIR "\${LLVM_INSTALL_PREFIX}")
-set(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}/bin")
+set(LLVM_CONFIG_TOOLS_BINARY_DIR "\${LLVM_INSTALL_PREFIX}/${CMAKE_INSTALL_BINDIR}")
 set(LLVM_CONFIG_EXPORTS_FILE "\${LLVM_CMAKE_DIR}/LLVMExports.cmake")
 set(LLVM_CONFIG_EXPORTS "${LLVM_EXPORTS}")
 configure_file(

cmake/modules/LLVMConfig.cmake.in

 set(LLVM_CMAKE_DIR "@LLVM_CONFIG_CMAKE_DIR@")
 set(LLVM_BINARY_DIR "@LLVM_CONFIG_BINARY_DIR@")
 set(LLVM_TOOLS_BINARY_DIR "@LLVM_CONFIG_TOOLS_BINARY_DIR@")
-set(LLVM_TOOLS_INSTALL_DIR "@LLVM_TOOLS_INSTALL_DIR@")
+set(LLVM_TOOLS_INSTALL_DIR "@CMAKE_INSTALL_BINDIR@")
 set(LLVM_HAVE_OPT_VIEWER_MODULES @LLVM_HAVE_OPT_VIEWER_MODULES@)
 
+set(CMAKE_INSTALL_BINDIR "@CMAKE_INSTALL_BINDIR@")
+set(CMAKE_INSTALL_LIBDIR "@CMAKE_INSTALL_LIBDIR@")
+set(CMAKE_INSTALL_INCLUDEDIR "@CMAKE_INSTALL_INCLUDEDIR@")
+set(CMAKE_INSTALL_DOCDIR "@CMAKE_INSTALL_DOCDIR@")
+set(CMAKE_INSTALL_MANDIR "@CMAKE_INSTALL_MANDIR@")
+
 if(NOT TARGET LLVMSupport)
   set(LLVM_EXPORTED_TARGETS "@LLVM_CONFIG_EXPORTS@")
   include("@LLVM_CONFIG_EXPORTS_FILE@")

cmake/modules/TableGen.cmake

 
     install(TARGETS ${target}
             ${export_to_llvmexports}
-            RUNTIME DESTINATION ${LLVM_TOOLS_INSTALL_DIR})
+            RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR})
   endif()
   set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS ${target})
 endmacro()

docs/CMake.rst

 **LLVM_LIBDIR_SUFFIX**:STRING
   Extra suffix to append to the directory where libraries are to be
   installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
-  to install libraries to ``/usr/lib64``.
+  to install libraries to ``/usr/lib64``. See also ``CMAKE_INSTALL_LIBDIR``.
 
 **CMAKE_C_FLAGS**:STRING
   Extra flags to use when compiling C source files.

 
 **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
+  `${CMAKE_INSTALL_DOCDIR}/${project}/doxygen-html`.
 
 **LLVM_ENABLE_SPHINX**:BOOL
   If specified, CMake will search for the ``sphinx-build`` executable and will make

 
 **LLVM_INSTALL_SPHINX_HTML_DIR**:STRING
   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`.
+  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
+  `${CMAKE_INSTALL_DOCDIR}/${project}/html`.
 
 **LLVM_INSTALL_OCAMLDOC_HTML_DIR**:STRING
   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`.
+  either be absolute or relative to the ``CMAKE_INSTALL_PREFIX``. Defaults to
+  `${CMAKE_INSTALL_DOCDIR}/${project}/ocaml-html`.
 
+**CMAKE_INSTALL_BINDIR**:STRING
+  The path to install binary tools, relative to the ``CMAKE_INSTALL_PREFIX``.
+  Defaults to `bin`.
+
+**CMAKE_INSTALL_LIBDIR**:STRING
+  The path to install libraries, relative to the ``CMAKE_INSTALL_PREFIX``.
+  Defaults to `lib`.
+
+**CMAKE_INSTALL_INCLUDEDIR**:STRING
+  The path to install header files, relative to the ``CMAKE_INSTALL_PREFIX``.
+  Defaults to `include`.
+
+**CMAKE_INSTALL_DOCDIR**:STRING
+  The path to install documentation, relative to the ``CMAKE_INSTALL_PREFIX``.
+  Defaults to `share/doc`.
+
+**CMAKE_INSTALL_MANDIR**:STRING
+  The path to install manpage files, relative to the ``CMAKE_INSTALL_PREFIX``.
+  Defaults to `share/man`.
+
 **LLVM_CREATE_XCODE_TOOLCHAIN**:BOOL
   OS X Only: If enabled CMake will generate a target named
   'install-xcode-toolchain'. This target will create a directory at

include/llvm/CMakeLists.txt

 # If we're doing an out-of-tree build, copy a module map for generated
 # header files into the build area.
 if (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")
-  configure_file(module.modulemap.build module.modulemap COPYONLY)
+  configure_file(module.modulemap.build ${LLVM_INCLUDE_DIR}/module.modulemap COPYONLY)
 endif (NOT "${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_BINARY_DIR}")

tools/llvm-config/BuildVariables.inc.in

 #define LLVM_CXXFLAGS "@LLVM_CXXFLAGS@"
 #define LLVM_BUILDMODE "@LLVM_BUILDMODE@"
 #define LLVM_LIBDIR_SUFFIX "@LLVM_LIBDIR_SUFFIX@"
+#define LLVM_INSTALL_BINDIR "@CMAKE_INSTALL_BINDIR@"
+#define LLVM_INSTALL_LIBDIR "@CMAKE_INSTALL_LIBDIR@"
+#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@"

tools/llvm-config/llvm-config.cpp

     DevelopmentTreeLayout = CMakeStyle;
     ActiveObjRoot = LLVM_OBJ_ROOT;
   } else if (sys::fs::equivalent(CurrentExecPrefix,
-                                 Twine(LLVM_OBJ_ROOT) + "/bin")) {
+                                 Twine(LLVM_OBJ_ROOT) + "/" + LLVM_INSTALL_BINDIR)) {
     IsInDevelopmentTree = true;
     DevelopmentTreeLayout = CMakeBuildModeStyle;
     ActiveObjRoot = LLVM_OBJ_ROOT;

               ActiveCMakeDir;
   std::string ActiveIncludeOption;
   if (IsInDevelopmentTree) {
-    ActiveIncludeDir = std::string(LLVM_SRC_ROOT) + "/include";
+    ActiveIncludeDir = std::string(LLVM_SRC_ROOT) + "/" + LLVM_INSTALL_INCLUDEDIR;
     ActivePrefix = CurrentExecPrefix;
 
     // CMake organizes the products differently than a normal prefix style

     // layout.
     switch (DevelopmentTreeLayout) {
     case CMakeStyle:
-      ActiveBinDir = ActiveObjRoot + "/bin";
-      ActiveLibDir = ActiveObjRoot + "/lib" + LLVM_LIBDIR_SUFFIX;
+      ActiveBinDir = ActiveObjRoot + "/" + LLVM_INSTALL_BINDIR;
+      ActiveLibDir = ActiveObjRoot + LLVM_INSTALL_LIBDIR + LLVM_LIBDIR_SUFFIX;
       ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
       break;
     case CMakeBuildModeStyle:
       ActivePrefix = ActiveObjRoot;
-      ActiveBinDir = ActiveObjRoot + "/bin/" + build_mode;
+      ActiveBinDir = ActiveObjRoot + "/" + LLVM_INSTALL_BINDIR + "/" + build_mode;
       ActiveLibDir =
-          ActiveObjRoot + "/lib" + LLVM_LIBDIR_SUFFIX + "/" + build_mode;
+          ActiveObjRoot + "/" + LLVM_INSTALL_LIBDIR + LLVM_LIBDIR_SUFFIX + "/" + build_mode;
       ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
       break;
     }

 
     // We need to include files from both the source and object trees.
     ActiveIncludeOption =
-        ("-I" + ActiveIncludeDir + " " + "-I" + ActiveObjRoot + "/include");
+        ("-I" + ActiveIncludeDir + " " + "-I" + ActiveObjRoot + "/" + LLVM_INSTALL_INCLUDEDIR);
   } else {
     ActivePrefix = CurrentExecPrefix;
-    ActiveIncludeDir = ActivePrefix + "/include";
-    SmallString<256> path(StringRef(LLVM_TOOLS_INSTALL_DIR));
+    ActiveIncludeDir = ActivePrefix + "/" + LLVM_INSTALL_INCLUDEDIR;
+    SmallString<256> path(StringRef(LLVM_INSTALL_BINDIR));
     sys::fs::make_absolute(ActivePrefix, path);
     ActiveBinDir = path.str();
-    ActiveLibDir = ActivePrefix + "/lib" + LLVM_LIBDIR_SUFFIX;
+    ActiveLibDir = ActivePrefix + "/" + LLVM_INSTALL_LIBDIR + LLVM_LIBDIR_SUFFIX;
     ActiveCMakeDir = ActiveLibDir + "/cmake/llvm";
     ActiveIncludeOption = "-I" + ActiveIncludeDir;
   }

tools/llvm-shlib/CMakeLists.txt

 
   set(LLVM_EXPORTED_SYMBOL_FILE ${CMAKE_BINARY_DIR}/libllvm-c.exports)
 
-  set(LIB_DIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX})
+  set(LIB_DIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX})
   set(LIB_NAME ${LIB_DIR}/${CMAKE_SHARED_LIBRARY_PREFIX}LLVM)
   set(LIB_PATH ${LIB_NAME}${CMAKE_SHARED_LIBRARY_SUFFIX})
   set(LIB_EXPORTS_PATH ${LIB_NAME}.exports)

tools/lto/CMakeLists.txt

 add_llvm_library(LTO SHARED ${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)