Index: clang/include/clang/Basic/SourceManager.h
===================================================================
--- clang/include/clang/Basic/SourceManager.h
+++ clang/include/clang/Basic/SourceManager.h
@@ -1463,8 +1463,11 @@
 
     // This happens when the macro is the result of a paste, in that case
     // its spelling is the scratch memory, so we take the parent context.
-    if (isWrittenInScratchSpace(getSpellingLoc(loc)))
-      return isInSystemHeader(getSpellingLoc(getImmediateMacroCallerLoc(loc)));
+    // There can be several level of token pasting.
+    if (isWrittenInScratchSpace(getSpellingLoc(loc))) {
+      do { loc = getImmediateMacroCallerLoc(loc); } while (isWrittenInScratchSpace(getSpellingLoc(loc)));
+      return isInSystemMacro(loc);
+    }
 
     return isInSystemHeader(getSpellingLoc(loc));
   }
Index: clang/test/Misc/no-warn-in-system-macro.c
===================================================================
--- clang/test/Misc/no-warn-in-system-macro.c
+++ clang/test/Misc/no-warn-in-system-macro.c
@@ -3,11 +3,16 @@
 
 #include <no-warn-in-system-macro.c.inc>
 
+#define MACRO(x) x
+
 int main(void)
 {
 	double foo = 1.0;
 
 	if (isnan(foo))
 		return 1;
+
+	MACRO(isnan(foo));
+
 	return 0;
 }