Corrected a typo in the building libc++ docs

llvm-svn: 319631
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 0bf99c69544785186ff1e84b6ff90cb9bf7d81ce
diff --git a/docs/BuildingLibcxx.rst b/docs/BuildingLibcxx.rst
index d983bbd..3dae2f4 100644
--- a/docs/BuildingLibcxx.rst
+++ b/docs/BuildingLibcxx.rst
@@ -130,7 +130,7 @@
           -DCMAKE_SYSTEM_NAME=Windows                                                 ^
           -DCMAKE_C_COMPILER=clang-cl                                                 ^
           -DCMAKE_C_FLAGS="-fms-compatibility-version=19.00 --target=i686--windows"   ^
-          -DCMAKE_CXX_COMPILER=clang-c                                                ^
+          -DCMAKE_CXX_COMPILER=clang-cl                                                ^
           -DCMAKE_CXX_FLAGS="-fms-compatibility-version=19.00 --target=i686--windows" ^
           -DLLVM_PATH=/path/to/llvm/tree                                              ^
           -DLIBCXX_ENABLE_SHARED=YES                                                  ^