Index: test/SemaTemplate/instantiate-expr-3.cpp
===================================================================
--- test/SemaTemplate/instantiate-expr-3.cpp	(revision 131721)
+++ test/SemaTemplate/instantiate-expr-3.cpp	(working copy)
@@ -117,3 +117,12 @@
 
 template struct VaArg1<__builtin_va_list, int>;
 template struct VaArg1<int, int>; // expected-note{{instantiation}}
+
+struct VaArg2 {
+  virtual void f(int n, ...) {
+    __builtin_va_list va;
+    __builtin_va_start(va, n);
+    (void)__builtin_va_arg(va, VaArg2); // expected-error {{second argument to 'va_arg' is of non-POD type 'VaArg2'}}
+    __builtin_va_end(va);
+  }
+};
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td	(revision 131721)
+++ include/clang/Basic/DiagnosticSemaKinds.td	(working copy)
@@ -3856,6 +3856,9 @@
   "second parameter of 'va_start' not last named argument">;
 def err_first_argument_to_va_arg_not_of_type_va_list : Error<
   "first argument to 'va_arg' is of type %0 and not 'va_list'">;
+def warn_second_parameter_to_va_arg_not_pod : Warning<
+  "second argument to 'va_arg' is of non-POD type %0">,
+  InGroup<DiagGroup<"non-pod-varargs">>, DefaultError;
 
 def warn_return_missing_expr : Warning<
   "non-void %select{function|method}1 %0 should return a value">, DefaultError,
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp	(revision 131721)
+++ lib/Sema/SemaExpr.cpp	(working copy)
@@ -9545,8 +9545,12 @@
   }
 
   // FIXME: Check that type is complete/non-abstract
-  // FIXME: Warn if a non-POD type is passed in.
 
+  if (!TInfo->getType()->isDependentType() && !TInfo->getType()->isPODType())
+    return ExprError(Diag(TInfo->getTypeLoc().getBeginLoc(),
+                         diag::warn_second_parameter_to_va_arg_not_pod)
+      << TInfo->getType() << TInfo->getTypeLoc().getSourceRange());
+
   QualType T = TInfo->getType().getNonLValueExprType(Context);
   return Owned(new (Context) VAArgExpr(BuiltinLoc, E, TInfo, RPLoc, T));
 }