Index: clang/lib/Lex/PPDirectives.cpp
===================================================================
--- clang/lib/Lex/PPDirectives.cpp
+++ clang/lib/Lex/PPDirectives.cpp
@@ -2639,7 +2639,7 @@
   SmallVector<IdentifierInfo*, 32> Parameters;
 
   while (true) {
-    LexUnexpandedToken(Tok);
+    LexUnexpandedNonComment(Tok);
     switch (Tok.getKind()) {
     case tok::r_paren:
       // Found the end of the parameter list.
Index: clang/test/Preprocessor/comment_save_macro.c
===================================================================
--- clang/test/Preprocessor/comment_save_macro.c
+++ clang/test/Preprocessor/comment_save_macro.c
@@ -1,13 +1,17 @@
 // RUN: %clang_cc1 -E -C %s | FileCheck -check-prefix=CHECK-C -strict-whitespace %s
 // CHECK-C: boo bork bar // zot
+// CHECK-C: ( 0);
 
 // RUN: %clang_cc1 -E -CC %s | FileCheck -check-prefix=CHECK-CC -strict-whitespace %s
 // CHECK-CC: boo bork /* blah*/ bar // zot
+// CHECK-CC: (/**/0);
 
 // RUN: %clang_cc1 -E %s | FileCheck -strict-whitespace %s
 // CHECK: boo bork bar
+// CHECK: ( 0);
 
 
 #define FOO bork // blah
 boo FOO bar // zot
-
+#define M(/**/x) (/**/x)
+M(0);