diff --git a/llvm/cmake/platforms/WinMsvc.cmake b/llvm/cmake/platforms/WinMsvc.cmake
--- a/llvm/cmake/platforms/WinMsvc.cmake
+++ b/llvm/cmake/platforms/WinMsvc.cmake
@@ -232,6 +232,7 @@
 set(CMAKE_C_COMPILER "${LLVM_NATIVE_TOOLCHAIN}/bin/clang-cl" CACHE FILEPATH "")
 set(CMAKE_CXX_COMPILER "${LLVM_NATIVE_TOOLCHAIN}/bin/clang-cl" CACHE FILEPATH "")
 set(CMAKE_LINKER "${LLVM_NATIVE_TOOLCHAIN}/bin/lld-link" CACHE FILEPATH "")
+set(CMAKE_AR "${LLVM_NATIVE_TOOLCHAIN}/bin/llvm-lib" CACHE FILEPATH "")
 
 # Even though we're cross-compiling, we need some native tools (e.g. llvm-tblgen), and those
 # native tools have to be built before we can start doing the cross-build.  LLVM supports