diff --git a/gcloud/_testing.py b/gcloud/_testing.py
index 15ef5dd298e1..0a440e817436 100644
--- a/gcloud/_testing.py
+++ b/gcloud/_testing.py
@@ -59,17 +59,3 @@ def __init__(self, items, page_token):
     def next(self):
         items, self._items = self._items, None
         return items
-
-
-class _GAXBundlingEvent(object):
-
-    result = None
-
-    def __init__(self, result):
-        self._result = result
-
-    def is_set(self):
-        return self.result is not None
-
-    def wait(self, *_):
-        self.result = self._result
diff --git a/gcloud/pubsub/_gax.py b/gcloud/pubsub/_gax.py
index 0639833feb73..28ac6c23e294 100644
--- a/gcloud/pubsub/_gax.py
+++ b/gcloud/pubsub/_gax.py
@@ -162,17 +162,17 @@ def topic_publish(self, topic_path, messages):
         :raises: :exc:`gcloud.exceptions.NotFound` if the topic does not
                     exist
         """
+        options = CallOptions(is_bundling=False)
         message_pbs = [_message_pb_from_dict(message)
                        for message in messages]
         try:
-            event = self._gax_api.publish(topic_path, message_pbs)
-            if not event.is_set():
-                event.wait()
+            result = self._gax_api.publish(topic_path, message_pbs,
+                                           options=options)
         except GaxError as exc:
             if exc_to_code(exc.cause) == StatusCode.NOT_FOUND:
                 raise NotFound(topic_path)
             raise
-        return event.result.message_ids
+        return result.message_ids
 
     def topic_list_subscriptions(self, topic_path, page_size=0,
                                  page_token=None):
diff --git a/gcloud/pubsub/test__gax.py b/gcloud/pubsub/test__gax.py
index d285cb6e3260..2426d2dfb7e8 100644
--- a/gcloud/pubsub/test__gax.py
+++ b/gcloud/pubsub/test__gax.py
@@ -204,15 +204,12 @@ def test_topic_delete_error(self):
 
     def test_topic_publish_hit(self):
         import base64
-        from gcloud._testing import _GAXBundlingEvent
         PAYLOAD = b'This is the message text'
         B64 = base64.b64encode(PAYLOAD).decode('ascii')
         MSGID = 'DEADBEEF'
         MESSAGE = {'data': B64, 'attributes': {}}
         response = _PublishResponsePB([MSGID])
-        event = _GAXBundlingEvent(response)
-        event.wait()  # already received result
-        gax_api = _GAXPublisherAPI(_publish_response=event)
+        gax_api = _GAXPublisherAPI(_publish_response=response)
         api = self._makeOne(gax_api)
 
         resource = api.topic_publish(self.TOPIC_PATH, [MESSAGE])
@@ -223,29 +220,7 @@ def test_topic_publish_hit(self):
         message_pb, = message_pbs
         self.assertEqual(message_pb.data, B64)
         self.assertEqual(message_pb.attributes, {})
-        self.assertEqual(options, None)
-
-    def test_topic_publish_hit_with_wait(self):
-        import base64
-        from gcloud._testing import _GAXBundlingEvent
-        PAYLOAD = b'This is the message text'
-        B64 = base64.b64encode(PAYLOAD).decode('ascii')
-        MSGID = 'DEADBEEF'
-        MESSAGE = {'data': B64, 'attributes': {}}
-        response = _PublishResponsePB([MSGID])
-        event = _GAXBundlingEvent(response)
-        gax_api = _GAXPublisherAPI(_publish_response=event)
-        api = self._makeOne(gax_api)
-
-        resource = api.topic_publish(self.TOPIC_PATH, [MESSAGE])
-
-        self.assertEqual(resource, [MSGID])
-        topic_path, message_pbs, options = gax_api._publish_called_with
-        self.assertEqual(topic_path, self.TOPIC_PATH)
-        message_pb, = message_pbs
-        self.assertEqual(message_pb.data, B64)
-        self.assertEqual(message_pb.attributes, {})
-        self.assertEqual(options, None)
+        self.assertEqual(options.is_bundling, False)
 
     def test_topic_publish_miss_w_attrs_w_bytes_payload(self):
         import base64
@@ -264,7 +239,7 @@ def test_topic_publish_miss_w_attrs_w_bytes_payload(self):
         message_pb, = message_pbs
         self.assertEqual(message_pb.data, B64)
         self.assertEqual(message_pb.attributes, {'foo': 'bar'})
-        self.assertEqual(options, None)
+        self.assertEqual(options.is_bundling, False)
 
     def test_topic_publish_error(self):
         import base64
@@ -283,7 +258,7 @@ def test_topic_publish_error(self):
         message_pb, = message_pbs
         self.assertEqual(message_pb.data, B64)
         self.assertEqual(message_pb.attributes, {})
-        self.assertEqual(options, None)
+        self.assertEqual(options.is_bundling, False)
 
     def test_topic_list_subscriptions_no_paging(self):
         from google.gax import INITIAL_PAGE