Index: cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
===================================================================
--- cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
+++ cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
@@ -2008,6 +2008,12 @@
         continue;
     }
 
+    // If the key function is dllimport but the class isn't, then the class has
+    // no key function. The DLL that exports the key function won't export the
+    // vtable in this case.
+    if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
+      return nullptr;
+
     // We found it.
     return MD;
   }
Index: cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp
===================================================================
--- cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp
+++ cfe/trunk/test/CodeGenCXX/dllimport-rtti.cpp
@@ -22,3 +22,11 @@
 // GNU-DAG: @_ZTV1V = available_externally dllimport
 // GNU-DAG: @_ZTS1V = linkonce_odr
 // GNU-DAG: @_ZTI1V = linkonce_odr
+
+struct W {
+  __declspec(dllimport) virtual void f();
+  virtual void g();
+} w;
+// GNU-DAG: @_ZTV1W = linkonce_odr
+// GNU-DAG: @_ZTS1W = linkonce_odr
+// GNU-DAG: @_ZTI1W = linkonce_odr