diff --git a/lib/Sema/SemaTemplateInstantiate.cpp b/lib/Sema/SemaTemplateInstantiate.cpp
index 5e4fde7..0c78c71 100644
--- a/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/lib/Sema/SemaTemplateInstantiate.cpp
@@ -560,6 +560,11 @@
 QualType
 TemplateTypeInstantiator::InstantiateDecltypeType(const DecltypeType *T,
                                                   unsigned Quals) const {
+  // C++0x [dcl.type.simple]p4:
+  //   The operand of the decltype specifier is an unevaluated operand.
+  EnterExpressionEvaluationContext Unevaluated(SemaRef,
+                                               Action::Unevaluated);
+  
   Sema::OwningExprResult E 
     = SemaRef.InstantiateExpr(T->getUnderlyingExpr(), TemplateArgs);