diff --git a/mypy/plugin.py b/mypy/plugin.py
index 3772d7039b05..201ec65748b9 100644
--- a/mypy/plugin.py
+++ b/mypy/plugin.py
@@ -257,6 +257,12 @@ def named_type(self, fullname: str,
         """Construct an instance of a builtin type with given type arguments."""
         raise NotImplementedError
 
+    @abstractmethod
+    def builtin_type(self, fully_qualified_name: str) -> Instance:
+        """Legacy function -- use named_type() instead."""
+        # NOTE: Do not delete this since many plugins may still use it.
+        raise NotImplementedError
+
     @abstractmethod
     def named_type_or_none(self, fullname: str,
                            args: Optional[List[Type]] = None) -> Optional[Instance]:
diff --git a/mypy/semanal.py b/mypy/semanal.py
index aca1f545c472..764fb4c36394 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -4567,6 +4567,10 @@ def named_type_or_none(self, fullname: str,
             return Instance(node, args)
         return Instance(node, [AnyType(TypeOfAny.unannotated)] * len(node.defn.type_vars))
 
+    def builtin_type(self, fully_qualified_name: str) -> Instance:
+        """Legacy function -- use named_type() instead."""
+        return self.named_type(fully_qualified_name)
+
     def lookup_current_scope(self, name: str) -> Optional[SymbolTableNode]:
         if self.locals[-1] is not None:
             return self.locals[-1].get(name)