Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -5439,10 +5439,6 @@
     return QualType(PrevDecl->TypeForDecl, 0);
   }
 
-  // Prefer the definition, if there is one.
-  if (const ObjCInterfaceDecl *Def = Decl->getDefinition())
-    Decl = Def;
-
   void *Mem = Allocate(sizeof(ObjCInterfaceType), TypeAlignment);
   auto *T = new (Mem) ObjCInterfaceType(Decl);
   Decl->TypeForDecl = T;