Index: lib/AST/Decl.cpp
===================================================================
--- lib/AST/Decl.cpp
+++ lib/AST/Decl.cpp
@@ -1184,7 +1184,7 @@
     return LinkageInfo::none();
 
   const Decl *OuterD = getOutermostFuncOrBlockContext(D);
-  if (!OuterD)
+  if (!OuterD || OuterD->isInvalidDecl())
     return LinkageInfo::none();
 
   LinkageInfo LV;
Index: test/SemaCXX/linkage-invalid-decl.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/linkage-invalid-decl.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+// This invalid declaration used to call infinite recursion in linkage
+// calculation for enum as a function argument.
+inline foo(A)(enum E;
+// expected-error@-1 {{unknown type name 'foo'}}
+// expected-error@-2 {{ISO C++ forbids forward references to 'enum' types}}
+// expected-error@-3 {{expected ')'}}
+// expected-note@-4 {{to match this '('}}