diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -599,6 +599,8 @@
   if (BUILD_SHARED_LIBS)
     message(FATAL_ERROR "BUILD_SHARED_LIBS options is not supported on Windows.")
   endif()
+  # Force MSVC to read code as UTF-8.
+  add_compile_options(/utf-8)
 else()
   option(LLVM_LINK_LLVM_DYLIB "Link tools against the libllvm dynamic library" OFF)
   option(LLVM_BUILD_LLVM_C_DYLIB "Build libllvm-c re-export library (Darwin only)" OFF)