diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -436,7 +436,7 @@ if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
   set(LIBCXX_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LLVM_DEFAULT_TARGET_TRIPLE})
   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}/${LLVM_DEFAULT_TARGET_TRIPLE} CACHE PATH
+  set(LIBCXX_INSTALL_LIBRARY_DIR "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}/${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE PATH
       "Path where built libc++ libraries should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${CMAKE_INSTALL_INCLUDEDIR}/${LLVM_DEFAULT_TARGET_TRIPLE}/c++/v1" CACHE PATH
       "Path where target-specific libc++ headers should be installed.")
@@ -453,7 +453,7 @@ else()
     set(LIBCXX_GENERATED_INCLUDE_DIR "${CMAKE_BINARY_DIR}/include/c++/v1")
   endif()
   set(LIBCXX_GENERATED_INCLUDE_TARGET_DIR "${LIBCXX_GENERATED_INCLUDE_DIR}")
-  set(LIBCXX_INSTALL_LIBRARY_DIR lib${LIBCXX_LIBDIR_SUFFIX} CACHE PATH
+  set(LIBCXX_INSTALL_LIBRARY_DIR "${CMAKE_INSTALL_LIBDIR}${LLVM_LIBDIR_SUFFIX}" CACHE PATH
       "Path where built libc++ libraries should be installed.")
   set(LIBCXX_INSTALL_INCLUDE_TARGET_DIR "${LIBCXX_INSTALL_INCLUDE_DIR}" CACHE PATH
       "Path where target-specific libc++ headers should be installed.")