diff --git a/zulip/zulip/__init__.py b/zulip/zulip/__init__.py
index 5d3e3cb..17f7724 100644
--- a/zulip/zulip/__init__.py
+++ b/zulip/zulip/__init__.py
@@ -434,6 +434,15 @@ class Client(object):
         if files is None:
             files = []
 
+        if longpolling:
+            # When long-polling, set timeout to 90 sec as a balance
+            # between a low traffic rate and a still reasonable latency
+            # time in case of a connection failure.
+            request_timeout = 90
+        else:
+            # Otherwise, 15s should be plenty of time.
+            request_timeout = 15
+
         request = {}
         req_files = []
 
@@ -491,10 +500,11 @@ class Client(object):
                 if files:
                     kwargs['files'] = req_files
 
+                # Actually make the request!
                 res = self.session.request(
                     method,
                     urllib.parse.urljoin(self.base_url, url),
-                    timeout=90,
+                    timeout=request_timeout,
                     **kwargs)
 
                 # On 50x errors, try again after a short sleep
@@ -547,7 +557,8 @@ class Client(object):
         # type: (str, str, Dict[str, Any], bool, List[IO]) -> Dict[str, Any]
         if request is None:
             request = dict()
-        return self.do_api_query(request, API_VERSTRING + url, method=method, files=files)
+        return self.do_api_query(request, API_VERSTRING + url, method=method,
+                                 longpolling=longpolling, files=files)
 
     def call_on_each_event(self, callback, event_types=None, narrow=None):
         # type: (Callable, Optional[List[str]], Any) -> None