diff --git a/changelog.d/4461.bugfix b/changelog.d/4461.bugfix
new file mode 100644
index 000000000..92062a2bf
--- /dev/null
+++ b/changelog.d/4461.bugfix
@@ -0,0 +1 @@
+Add a timeout to filtered room directory queries.
\ No newline at end of file
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index dc8862088..13e212d66 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -73,8 +73,14 @@ class RoomListHandler(BaseHandler):
             # We explicitly don't bother caching searches or requests for
             # appservice specific lists.
             logger.info("Bypassing cache as search request.")
+
+            # XXX: Quick hack to stop room directory queries taking too long.
+            # Timeout request after 60s. Probably want a more fundamental
+            # solution at some point
+            timeout = self.clock.time() + 60
             return self._get_public_room_list(
-                limit, since_token, search_filter, network_tuple=network_tuple,
+                limit, since_token, search_filter,
+                network_tuple=network_tuple, timeout=timeout,
             )
 
         key = (limit, since_token, network_tuple)
@@ -87,7 +93,8 @@ class RoomListHandler(BaseHandler):
     @defer.inlineCallbacks
     def _get_public_room_list(self, limit=None, since_token=None,
                               search_filter=None,
-                              network_tuple=EMPTY_THIRD_PARTY_ID,):
+                              network_tuple=EMPTY_THIRD_PARTY_ID,
+                              timeout=None,):
         if since_token and since_token != "END":
             since_token = RoomListNextBatch.from_token(since_token)
         else:
@@ -202,6 +209,9 @@ class RoomListHandler(BaseHandler):
 
         chunk = []
         for i in range(0, len(rooms_to_scan), step):
+            if timeout and self.clock.time() > timeout:
+                raise Exception("Timed out searching room directory")
+
             batch = rooms_to_scan[i:i + step]
             logger.info("Processing %i rooms for result", len(batch))
             yield concurrently_execute(