diff --git a/django/core/cache/backends/locmem.py b/django/core/cache/backends/locmem.py
index 7421b9b158..59293527b7 100644
--- a/django/core/cache/backends/locmem.py
+++ b/django/core/cache/backends/locmem.py
@@ -87,6 +87,22 @@ class LocMemCache(BaseCache):
         finally:
             self._lock.writer_leaves()
 
+    def incr(self, key, delta=1, version=None):
+        value = self.get(key, version=version)
+        if value is None:
+            raise ValueError("Key '%s' not found" % key)
+        new_value = value + delta
+        key = self.make_key(key, version=version)
+        self._lock.writer_enters()
+        try:
+            pickled = pickle.dumps(new_value, pickle.HIGHEST_PROTOCOL)
+            self._cache[key] = pickled
+        except pickle.PickleError:
+            pass
+        finally:
+            self._lock.writer_leaves()
+        return new_value
+
     def has_key(self, key, version=None):
         key = self.make_key(key, version=version)
         self.validate_key(key)
diff --git a/tests/regressiontests/cache/tests.py b/tests/regressiontests/cache/tests.py
index c5dc4576e2..307588c4ea 100644
--- a/tests/regressiontests/cache/tests.py
+++ b/tests/regressiontests/cache/tests.py
@@ -865,6 +865,16 @@ class LocMemCacheTests(unittest.TestCase, BaseCacheTests):
         self.assertEqual(mirror_cache.get('value1'), 42)
         self.assertEqual(other_cache.get('value1'), None)
 
+    def test_incr_decr_timeout(self):
+        """incr/decr does not modify expiry time (matches memcached behavior)"""
+        key = 'value'
+        _key = self.cache.make_key(key)
+        self.cache.set(key, 1, timeout=self.cache.default_timeout*10)
+        expire = self.cache._expire_info[_key]
+        self.cache.incr(key)
+        self.assertEqual(expire, self.cache._expire_info[_key])
+        self.cache.decr(key)
+        self.assertEqual(expire, self.cache._expire_info[_key])
 
 # memcached backend isn't guaranteed to be available.
 # To check the memcached backend, the test settings file will