diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index ca4702d..763ef28 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -2927,6 +2927,7 @@
   case UTT_IsEmpty:
   case UTT_IsPolymorphic:
   case UTT_IsAbstract:
+  case UTT_IsInterfaceClass:
     // Fall-through
 
   // These traits require a complete type.
@@ -3057,6 +3058,10 @@
     if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
       return RD->isAbstract();
     return false;
+  case UTT_IsInterfaceClass:
+    if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
+      return RD->isInterface();
+    return false;
   case UTT_IsFinal:
     if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
       return RD->hasAttr<FinalAttr>();