Index: compiler-rt/trunk/cmake/Modules/CustomLibcxx/CMakeLists.txt
===================================================================
--- compiler-rt/trunk/cmake/Modules/CustomLibcxx/CMakeLists.txt
+++ compiler-rt/trunk/cmake/Modules/CustomLibcxx/CMakeLists.txt
@@ -1,4 +1,5 @@
 cmake_minimum_required(VERSION 3.4.3)
+project(custom-libcxx C CXX)
 
 # Build static libcxxabi.
 set(LIBCXXABI_STANDALONE_BUILD 1)