Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -561,6 +561,9 @@
   # but in many objects files need more than that. This flag is to increase the
   # number of sections.
   append("/bigobj" CMAKE_CXX_FLAGS)
+
+  # Standards conformance
+  append("/permissive-" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
 endif( MSVC )
 
 # Warnings-as-errors handling for GCC-compatible compilers: