diff --git a/requests/sessions.py b/requests/sessions.py
index 023edfbd31..f987306497 100644
--- a/requests/sessions.py
+++ b/requests/sessions.py
@@ -535,8 +535,13 @@ def send(self, request, **kwargs):
         if not isinstance(request, PreparedRequest):
             raise ValueError('You can only send PreparedRequests.')
 
+        checked_urls = set()
         while request.url in self.redirect_cache:
-            request.url = self.redirect_cache.get(request.url)
+            checked_urls.add(request.url)
+            new_url = self.redirect_cache.get(request.url)
+            if new_url in checked_urls:
+                break
+            request.url = new_url
 
         # Set up variables needed for resolve_redirects and dispatching of hooks
         allow_redirects = kwargs.pop('allow_redirects', True)