diff -r c6892ce7e56f Lib/calendar.py
--- a/Lib/calendar.py	Mon Sep 17 09:01:03 2012 +0200
+++ b/Lib/calendar.py	Fri Sep 21 00:13:56 2012 +0200
@@ -161,7 +161,11 @@
         oneday = datetime.timedelta(days=1)
         while True:
             yield date
-            date += oneday
+            try:
+                date += oneday
+            except OverflowError:
+                # Adding one day could result a date out of range
+                break
             if date.month != month and date.weekday() == self.firstweekday:
                 break
 
diff -r c6892ce7e56f Lib/test/test_calendar.py
--- a/Lib/test/test_calendar.py	Mon Sep 17 09:01:03 2012 +0200
+++ b/Lib/test/test_calendar.py	Fri Sep 21 00:13:56 2012 +0200
@@ -6,6 +6,7 @@
 import time
 import locale
 import sys
+import datetime
 
 result_2004_01_text = """
     January 2004
@@ -464,6 +465,10 @@
         new_october = calendar.TextCalendar().formatmonthname(2010, 10, 10)
         self.assertEqual(old_october, new_october)
 
+    def test_itermonthdates(self):
+        # ensure itermonthdates works for all months
+        list(calendar.Calendar().itermonthdates(datetime.MAXYEAR, 12))
+
 
 class MonthCalendarTestCase(unittest.TestCase):
     def setUp(self):