diff -r 40e291815b35 Lib/test/test_subclassinit.py
--- a/Lib/test/test_subclassinit.py	Mon Sep 19 22:20:13 2016 -0700
+++ b/Lib/test/test_subclassinit.py	Tue Sep 20 19:55:17 2016 +0300
@@ -148,6 +148,18 @@ class Test(unittest.TestCase):
             class A:
                 d = Descriptor()
 
+    def test_set_name_lookup(self):
+        resolved = []
+        class NonDescriptor:
+            def __getattr__(self, name):
+                resolved.append(name)
+
+        class A:
+            d = NonDescriptor()
+
+        if '__set_name__' in resolved:
+            self.fail('__set_name__ is looked up in instance dict')
+
     def test_set_name_init_subclass(self):
         class Descriptor:
             def __set_name__(self, owner, name):
diff -r 40e291815b35 Objects/typeobject.c
--- a/Objects/typeobject.c	Mon Sep 19 22:20:13 2016 -0700
+++ b/Objects/typeobject.c	Tue Sep 20 19:55:17 2016 +0300
@@ -6990,19 +6990,20 @@ update_all_slots(PyTypeObject* type)
 static int
 set_names(PyTypeObject *type)
 {
-    PyObject *key, *value, *tmp;
+    PyObject *key, *value, *set_name, *tmp;
     Py_ssize_t i = 0;
 
     while (PyDict_Next(type->tp_dict, &i, &key, &value)) {
-        if (PyObject_HasAttr(value, _PyUnicode_FromId(&PyId___set_name__))) {
-            tmp = PyObject_CallMethodObjArgs(
-                value, _PyUnicode_FromId(&PyId___set_name__),
-                type, key, NULL);
+        set_name = lookup_maybe(value, &PyId___set_name__);
+        if (set_name != NULL) {
+            tmp = PyObject_CallFunctionObjArgs(set_name, type, key, NULL);
             if (tmp == NULL)
                 return -1;
             else
                 Py_DECREF(tmp);
         }
+        else if (PyErr_Occurred())
+            return -1;
     }
 
     return 0;