diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index eacf367..004e31a 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1196,6 +1196,11 @@
     return true;
   }
 
+  // If this type hasn't been deduced yet, then conservatively assume that
+  // it'll work out to be a literal type.
+  if (isa<AutoType>(BaseTy->getCanonicalTypeInternal()))
+    return true;
+
   return false;
 }
 
diff --git a/test/SemaCXX/constant-expression-cxx1y.cpp b/test/SemaCXX/constant-expression-cxx1y.cpp
index ea0c9e6..23b5d0b 100644
--- a/test/SemaCXX/constant-expression-cxx1y.cpp
+++ b/test/SemaCXX/constant-expression-cxx1y.cpp
@@ -708,3 +708,10 @@
   static_assert(test_copy("hello world", 10), "");
   static_assert(test_copy("hello world", 10), "");
 }
+
+namespace deduced_return_type {
+  constexpr auto f() { return 0; }
+  template<typename T> constexpr auto g(T t) { return t; }
+  static_assert(f() == 0, "");
+  static_assert(g(true), "");
+}