Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -366,6 +366,21 @@
           CMAKE_SHARED_LINKER_FLAGS)
   endif()
 
+  OPTION(LLVM_ENABLE_DEBUG_GHASH OFF)
+  if (LLVM_ENABLE_DEBUG_GHASH)
+    if (CLANG_CL AND LINKER_IS_LLD_LINK)
+      append("-mllvm -emit-codeview-ghash-section" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
+      append("/DEBUG:GHASH" CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+    else()
+      if (NOT CLANG_CL)
+        message(WARNING "Option LLVM_ENABLE_DEBUG_GHASH is incompatible with cl.exe, clang-cl is required.")
+      endif()
+      if (NOT LINKER_IS_LLD_LINK)
+        message(WARNING "Option LLVM_ENABLE_DEBUG_GHASH is incompatible with link.exe, lld-link is required.")
+      endif()
+    endif()
+  endif()
+
   # /Zc:strictStrings is incompatible with VS12's (Visual Studio 2013's)
   # debug mode headers. Instead of only enabling them in VS2013's debug mode,
   # we'll just enable them for Visual Studio 2015 (VS 14, MSVC_VERSION 1900)