Index: CMakeLists.txt
===================================================================
--- CMakeLists.txt
+++ CMakeLists.txt
@@ -66,8 +66,10 @@
   # Windows where we need to use clang-cl instead.
   if(NOT MSVC)
     set(COMPILER_RT_TEST_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang)
+    set(COMPILER_RT_TEST_CXX_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++)
   else()
     set(COMPILER_RT_TEST_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang.exe)
+    set(COMPILER_RT_TEST_CXX_COMPILER ${LLVM_RUNTIME_OUTPUT_INTDIR}/clang++.exe)
   endif()
 else()
   # Take output dir and install path from the user.
Index: cmake/Modules/AddCompilerRT.cmake
===================================================================
--- cmake/Modules/AddCompilerRT.cmake
+++ cmake/Modules/AddCompilerRT.cmake
@@ -293,11 +293,12 @@
     SOURCE_DIR ${COMPILER_RT_LIBCXX_PATH}
     CMAKE_ARGS -DCMAKE_MAKE_PROGRAM:STRING=${CMAKE_MAKE_PROGRAM}
                -DCMAKE_C_COMPILER=${COMPILER_RT_TEST_COMPILER}
-               -DCMAKE_CXX_COMPILER=${COMPILER_RT_TEST_COMPILER}
+               -DCMAKE_CXX_COMPILER=${COMPILER_RT_TEST_CXX_COMPILER}
                -DCMAKE_C_FLAGS=${LIBCXX_CFLAGS}
                -DCMAKE_CXX_FLAGS=${LIBCXX_CFLAGS}
                -DCMAKE_BUILD_TYPE=Release
                -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR>
+               -DLLVM_PATH=${LLVM_SOURCE_DIR}
     LOG_BUILD 1
     LOG_CONFIGURE 1
     LOG_INSTALL 1