diff --git a/daphne/cli.py b/daphne/cli.py
index 7361914..d9d9fb4 100755
--- a/daphne/cli.py
+++ b/daphne/cli.py
@@ -86,7 +86,7 @@ class CommandLineInterface(object):
             "--http-timeout",
             type=int,
             help="How long to wait for worker before timing out HTTP connections",
-            default=120,
+            default=None,
         )
         self.parser.add_argument(
             "--access-log",
diff --git a/daphne/http_protocol.py b/daphne/http_protocol.py
index 060aab5..2c946e1 100755
--- a/daphne/http_protocol.py
+++ b/daphne/http_protocol.py
@@ -256,8 +256,12 @@ class WebRequest(http.Request):
         Called periodically to see if we should timeout something
         """
         # Web timeout checking
-        if self.duration() > self.server.http_timeout:
-            self.basic_error(503, b"Service Unavailable", "Application failed to respond within time limit.")
+        if self.server.http_timeout and self.duration() > self.server.http_timeout:
+            if self._response_started:
+                logger.warning("Application timed out while sending response")
+                self.finish()
+            else:
+                self.basic_error(503, b"Service Unavailable", "Application failed to respond within time limit.")
 
     ### Utility functions
 
diff --git a/daphne/server.py b/daphne/server.py
index c9ab4a3..6a65ebb 100755
--- a/daphne/server.py
+++ b/daphne/server.py
@@ -42,7 +42,7 @@ class Server(object):
         endpoints=None,
         signal_handlers=True,
         action_logger=None,
-        http_timeout=120,
+        http_timeout=None,
         websocket_timeout=86400,
         websocket_connect_timeout=20,
         ping_interval=20,