Index: cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- cmake/modules/HandleLLVMOptions.cmake
+++ cmake/modules/HandleLLVMOptions.cmake
@@ -354,9 +354,10 @@
   append("/Zc:inline" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 
   # Generate PDB even in release for profiling.
-  if (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
+  option(LLVM_ENABLE_GEN_PDB ON)
+  if (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE" AND LLVM_ENABLE_GEN_PDB)
     append("/Zi" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
-    append("/DEBUG" CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+    append("/DEBUG /OPT:REF /OPT:ICF" CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
   endif (uppercase_CMAKE_BUILD_TYPE STREQUAL "RELEASE")
 
   # /Zc:strictStrings is incompatible with VS12's (Visual Studio 2013's)