Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -242,6 +242,8 @@
 endif()
 
 set(LLVM_LIBDIR_SUFFIX "" CACHE STRING "Define suffix of library directory name (32/64)" )
+set(LLVM_RUNTIMES_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
+  "Define suffix of library directory used to hold runtimes (32/64)")
 
 set(LLVM_TOOLS_INSTALL_DIR "bin" CACHE STRING "Path for binary subdirectory (defaults to 'bin')")
 mark_as_advanced(LLVM_TOOLS_INSTALL_DIR)
Index: cmake/modules/LLVMConfig.cmake.in
===================================================================
--- cmake/modules/LLVMConfig.cmake.in
+++ cmake/modules/LLVMConfig.cmake.in
@@ -51,6 +51,7 @@
 set(LLVM_ON_WIN32 @LLVM_ON_WIN32@)
 
 set(LLVM_LIBDIR_SUFFIX @LLVM_LIBDIR_SUFFIX@)
+set(LLVM_RUNTIMES_LIBDIR_SUFFIX @LLVM_RUNTIMES_LIBDIR_SUFFIX@)
 
 set(LLVM_INCLUDE_DIRS "@LLVM_CONFIG_INCLUDE_DIRS@")
 set(LLVM_LIBRARY_DIRS "@LLVM_CONFIG_LIBRARY_DIRS@")
Index: docs/CMake.rst
===================================================================
--- docs/CMake.rst
+++ docs/CMake.rst
@@ -196,6 +196,12 @@
   installed. On a 64-bit architecture, one could use ``-DLLVM_LIBDIR_SUFFIX=64``
   to install libraries to ``/usr/lib64``.
 
+**LLVM_RUNTIMES_LIBDIR_SUFFIX**:STRING
+  Extra suffix to append to the library directory where LLVM runtimes
+  are to be installed. Defaults to LLVM_LIBDIR_SUFFIX. One can override
+  it to share a single runtime directory between 64-bit and 32-bit LLVM
+  builds.
+
 **CMAKE_C_FLAGS**:STRING
   Extra flags to use when compiling C source files.