Index: lib/Lex/PPLexerChange.cpp
===================================================================
--- lib/Lex/PPLexerChange.cpp
+++ lib/Lex/PPLexerChange.cpp
@@ -378,6 +378,8 @@
         Result.startToken();
         CurLexer->FormTokenWithChars(Result, CurLexer->BufferEnd, tok::eof);
         CurLexer.reset();
+        if (CurLexerKind == CLK_Lexer)
+          CurLexerKind = CLK_CachingLexer;
       } else {
         assert(CurPTHLexer && "Got EOF but no current lexer set!");
         CurPTHLexer->getEOF(Result);
Index: test/CodeCompletion/include-within-declaration.c
===================================================================
--- /dev/null
+++ test/CodeCompletion/include-within-declaration.c
@@ -0,0 +1,11 @@
+// RUN: rm -rf %t && mkdir %t
+// RUN: echo 'MACRO(here)' > %t/y.h
+// Clang will generate an error in this case (though internally the correct completions
+// are present -- this can be seen via libclang) but it should not crash. If it crashes
+// then `not` will fail, otherwise the test succeeds.
+// RUN: not %clang_cc1 -fsyntax-only -code-completion-at=%t/y.h:1:7 -I %t %s
+
+enum {
+#define MACRO(a) FOO
+#include "y.h"
+};