This relands commit r291728. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292084 91177308-0d34-0410-b5e6-96231b3b80d8
This relands commit r291728. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@292084 91177308-0d34-0410-b5e6-96231b3b80d8