diff --git a/llvm/cmake/config-ix.cmake b/llvm/cmake/config-ix.cmake
--- a/llvm/cmake/config-ix.cmake
+++ b/llvm/cmake/config-ix.cmake
@@ -663,3 +663,8 @@
 else()
   set (LLVM_HAVE_OPT_VIEWER_MODULES 0)
 endif()
+
+# Windows 7 or later
+if (MINGW)
+  add_definitions(-DWINVER=0x601 -D_WIN32_WINNT=0x601)
+endif()