diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 585599a..e8e57cb 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -288,6 +288,8 @@
     else if (!LangOpts.GNUMode && LangOpts.Digraphs)
       Builder.defineMacro("__STDC_VERSION__", "199409L");
   } else {
+    // FIXME: LangOpts.CPlusPlus1y
+
     // C++11 [cpp.predefined]p1:
     //   The name __cplusplus is defined to the value 201103L when compiling a
     //   C++ translation unit.