diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index d877520..85a65a4 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -2628,34 +2628,87 @@
   }
 }
 
+/// \brief Check the completeness of a type in a unary type trait.
+///
+/// If the particular type trait requires a complete type, tries to complete
+/// it. If completing the type fails, a diagnostic is emitted and false
+/// returned. If completing the type succeeds or no completion was required,
+/// returns true.
+static bool CheckUnaryTypeTraitTypeCompleteness(Sema &S,
+                                                UnaryTypeTrait UTT,
+                                                SourceLocation Loc,
+                                                QualType ArgTy) {
+  // C++0x [meta.unary.prop]p3:
+  //   For all of the class templates X declared in this Clause, instantiating
+  //   that template with a template argument that is a class template
+  //   specialization may result in the implicit instantiation of the template
+  //   argument if and only if the semantics of X require that the argument
+  //   must be a complete type.
+  // We apply this rule to all the type trait expressions used to implement
+  // these class templates. We also try to follow any GCC documented behavior
+  // in these expressions to ensure portability of standard libraries.
+  switch (UTT) {
+    // is_complete_type somewhat obviously cannot require a complete type.
+  case UTT_IsCompleteType:
+    return true;
+
+    // According to http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
+    // all traits except __is_class, __is_enum and __is_union require a the type
+    // to be complete, an array of unknown bound, or void.
+  case UTT_IsClass:
+  case UTT_IsEnum:
+  case UTT_IsUnion:
+    return true;
+
+  default:
+    // Apprantely Borland only wants the explicitly listed traits to complete
+    // the type.
+    if (S.LangOpts.Borland) return true;
+
+    // C++0x [meta.unary.prop] Table 49 requires the following traits to be
+    // applied to a complete type, so we enumerate theme here even though the
+    // default for non-Borland compilers is to require completeness for any
+    // other traits than the ones specifically allowed to work on incomplete
+    // types.
+    // FIXME: C++0x: This list is incomplete, and the names don't always
+    // correspond clearly to entries in the standard's table.
+  case UTT_HasNothrowAssign:
+  case UTT_HasNothrowConstructor:
+  case UTT_HasNothrowCopy:
+  case UTT_HasTrivialAssign:
+  case UTT_HasTrivialConstructor:
+  case UTT_HasTrivialCopy:
+  case UTT_HasTrivialDestructor:
+  case UTT_HasVirtualDestructor:
+  case UTT_IsAbstract:
+  case UTT_IsEmpty:
+  case UTT_IsLiteral:
+  case UTT_IsPOD:
+  case UTT_IsPolymorphic:
+  case UTT_IsStandardLayout:
+  case UTT_IsTrivial:
+    // Arrays of unknown bound are expressly allowed.
+    QualType ElTy = ArgTy;
+    if (ArgTy->isIncompleteArrayType())
+      ElTy = S.Context.getAsArrayType(ArgTy)->getElementType();
+
+    // The void type is expressly allowed.
+    if (ElTy->isVoidType())
+      return true;
+
+    return !S.RequireCompleteType(
+      Loc, ElTy, diag::err_incomplete_type_used_in_type_trait_expr);
+  }
+}
+
+
 ExprResult Sema::BuildUnaryTypeTrait(UnaryTypeTrait UTT,
                                      SourceLocation KWLoc,
                                      TypeSourceInfo *TSInfo,
                                      SourceLocation RParen) {
   QualType T = TSInfo->getType();
-
-  // According to http://gcc.gnu.org/onlinedocs/gcc/Type-Traits.html
-  // all traits except __is_class, __is_enum and __is_union require a the type
-  // to be complete, an array of unknown bound, or void.
-  if (UTT != UTT_IsClass && UTT != UTT_IsEnum && UTT != UTT_IsUnion &&
-      UTT != UTT_IsCompleteType) {
-    QualType E = T;
-    if (T->isIncompleteArrayType())
-      E = Context.getAsArrayType(T)->getElementType();
-    if (!T->isVoidType() &&
-        (! LangOpts.Borland ||
-         UTT == UTT_HasNothrowAssign ||
-         UTT == UTT_HasNothrowCopy ||
-         UTT == UTT_HasNothrowConstructor ||
-         UTT == UTT_HasTrivialAssign ||
-         UTT == UTT_HasTrivialCopy ||
-         UTT == UTT_HasTrivialConstructor ||
-         UTT == UTT_HasTrivialDestructor ||
-         UTT == UTT_HasVirtualDestructor) &&
-        RequireCompleteType(KWLoc, E,
-                            diag::err_incomplete_type_used_in_type_trait_expr))
-      return ExprError();
-  }
+  if (!CheckUnaryTypeTraitTypeCompleteness(*this, UTT, KWLoc, T))
+    return ExprError();
 
   bool Value = false;
   if (!T->isDependentType())