diff --git a/django/http/__init__.py b/django/http/__init__.py
index e585a713de..46232bee18 100644
--- a/django/http/__init__.py
+++ b/django/http/__init__.py
@@ -1,5 +1,7 @@
+import datetime
 import os
 import re
+import time
 from Cookie import BaseCookie, SimpleCookie, CookieError
 from pprint import pformat
 from urllib import urlencode
@@ -12,6 +14,7 @@ except ImportError:
 
 from django.utils.datastructures import MultiValueDict, ImmutableList
 from django.utils.encoding import smart_str, iri_to_uri, force_unicode
+from django.utils.http import cookie_date
 from django.http.multipartparser import MultiPartParser
 from django.conf import settings
 from django.core.files import uploadhandler
@@ -373,11 +376,32 @@ class HttpResponse(object):
 
     def set_cookie(self, key, value='', max_age=None, expires=None, path='/',
                    domain=None, secure=False):
+        """
+        Sets a cookie.
+
+        ``expires`` can be a string in the correct format or a 
+        ``datetime.datetime`` object in UTC. If ``expires`` is a datetime
+        object then ``max_age`` will be calculated.
+        """
         self.cookies[key] = value
+        if expires is not None:
+            if isinstance(expires, datetime.datetime):
+                delta = expires - expires.utcnow()
+                # Add one second so the date matches exactly (a fraction of
+                # time gets lost between converting to a timedelta and
+                # then the date string).
+                delta = delta + datetime.timedelta(seconds=1)
+                # Just set max_age - the max_age logic will set expires.
+                expires = None
+                max_age = max(0, delta.days * 86400 + delta.seconds)
+            else:
+                self.cookies[key]['expires'] = expires
         if max_age is not None:
             self.cookies[key]['max-age'] = max_age
-        if expires is not None:
-            self.cookies[key]['expires'] = expires
+            # IE requires expires, so set it if hasn't been already.
+            if not expires:
+                self.cookies[key]['expires'] = cookie_date(time.time() +
+                                                           max_age) 
         if path is not None:
             self.cookies[key]['path'] = path
         if domain is not None:
diff --git a/docs/ref/request-response.txt b/docs/ref/request-response.txt
index fb38b596e9..b8b08829e9 100644
--- a/docs/ref/request-response.txt
+++ b/docs/ref/request-response.txt
@@ -529,8 +529,11 @@ Methods
 
         * ``max_age`` should be a number of seconds, or ``None`` (default) if
           the cookie should last only as long as the client's browser session.
-        * ``expires`` should be a string in the format
-          ``"Wdy, DD-Mon-YY HH:MM:SS GMT"``.
+          If ``expires`` is not specified, it will be calculated.
+        * ``expires`` should either be a string in the format
+          ``"Wdy, DD-Mon-YY HH:MM:SS GMT"`` or a ``datetime.datetime`` object
+          in UTC. If ``expires`` is a ``datetime`` object, the ``max_age``
+          will be calculated.
         * Use ``domain`` if you want to set a cross-domain cookie. For example,
           ``domain=".lawrence.com"`` will set a cookie that is readable by
           the domains www.lawrence.com, blogs.lawrence.com and
diff --git a/tests/regressiontests/requests/tests.py b/tests/regressiontests/requests/tests.py
index 1615a73406..22bc88c172 100644
--- a/tests/regressiontests/requests/tests.py
+++ b/tests/regressiontests/requests/tests.py
@@ -1,5 +1,5 @@
 """
->>> from django.http import HttpRequest
+>>> from django.http import HttpRequest, HttpResponse
 >>> print repr(HttpRequest())
 <HttpRequest
 GET:{},
@@ -44,4 +44,27 @@ https://www.example.com/asdf
 >>> request.path = ''
 >>> print request.build_absolute_uri(location="/path/with:colons")
 http://www.example.com/path/with:colons
+
+
+# Test cookie datetime expiration logic
+>>> from datetime import datetime, timedelta
+>>> delta = timedelta(seconds=10)
+>>> response = HttpResponse()
+>>> response.set_cookie('datetime', expires=datetime.utcnow()+delta)
+>>> datetime_cookie = response.cookies['datetime']
+>>> datetime_cookie['max-age']
+10
+>>> response.set_cookie('datetime', expires=datetime(2028, 1, 1, 4, 5, 6))
+>>> response.cookies['datetime']['expires']
+'Sat, 01-Jan-2028 04:05:06 GMT'
+
+# Test automatically setting cookie expires if only max_age is provided 
+>>> response.set_cookie('max_age', max_age=10)
+>>> max_age_cookie = response.cookies['max_age']
+>>> max_age_cookie['max-age']
+10
+>>> from django.utils.http import cookie_date
+>>> import time
+>>> max_age_cookie['expires'] == cookie_date(time.time()+10)
+True
 """