diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index d66c374..e2dbb83 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -1647,8 +1647,11 @@
 
 void CXXNameMangler::mangleType(const AutoType *T) {
   QualType D = T->getDeducedType();
-  assert(!D.isNull() && "can't mangle undeduced auto type");
-  mangleType(D);
+  // <builtin-type> ::= Da  # dependent auto
+  if (D.isNull())
+    Out << "Da";
+  else
+    mangleType(D);
 }
 
 void CXXNameMangler::mangleIntegerLiteral(QualType T,
diff --git a/test/CodeGenCXX/mangle-exprs.cpp b/test/CodeGenCXX/mangle-exprs.cpp
index 7322171..e5f26e5 100644
--- a/test/CodeGenCXX/mangle-exprs.cpp
+++ b/test/CodeGenCXX/mangle-exprs.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-apple-darwin9 | FileCheck %s
+// RUN: %clang_cc1 -std=c++0x -emit-llvm %s -o - -triple=x86_64-apple-darwin9 | FileCheck %s
 
 template < bool condition, typename T = void >
 struct enable_if { typedef T type; };
@@ -24,6 +24,10 @@
   void static_(typename enable_if< O <= static_cast<unsigned>(4) >::type* = 0) {
   }
 
+  template< typename T >
+  void auto_(decltype(new auto(T()))) {
+  }
+
   // FIXME: Test const_cast, reinterpret_cast, dynamic_cast, which are
   // a bit harder to use in template arguments.
   template <unsigned N> struct T {};
@@ -41,4 +45,7 @@
 
   // CHECK: define weak_odr void @_ZN5Casts1fILi6EEENS_1TIXT_EEEv
   template T<6> f<6>();
+
+  // CHECK: define weak_odr void @_ZN5Casts5auto_IiEEvDTnw_DapicvT__EEE(
+  template void auto_<int>(int*);
 }