foo.diff

diff --git a/django/db/models/query.py b/django/db/models/query.py
index 34e8dab..55b9ab3 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -1620,9 +1620,10 @@ class RawQuerySet(object):
 
 
 class Prefetch(object):
-    def __init__(self, lookup, queryset=None):
+    def __init__(self, lookup, queryset=None, parent_filter=None):
         self.lookup = lookup
         self.queryset = queryset
+        self.parent_filter = parent_filter
 
 
 def normalize_prefetch_lookups(lookups, prefix=None):
@@ -1646,7 +1647,7 @@ def normalize_prefetch_lookups(lookups, prefix=None):
         # Then we apply a prefix if needed.
         if prefix:
             to_attr = LOOKUP_SEP.join([prefix, to_attr])
-            prefetch = Prefetch(LOOKUP_SEP.join([prefix, prefetch.lookup]), prefetch.queryset)
+            prefetch = Prefetch(LOOKUP_SEP.join([prefix, prefetch.lookup]), prefetch.queryset, prefetch.parent_filter)
 
         ret.append((to_attr, prefetch))
     ret.sort(key=lambda x: x[0])
@@ -1844,6 +1845,9 @@ def prefetch_one_level(instances, prefetcher, to_attr, lookup):
     # The 'values to be matched' must be hashable as they will be used
     # in a dictionary.
 
+    if lookup.parent_filter:
+        instances = filter(lookup.parent_filter, instances)
+
     rel_qs, rel_obj_attr, instance_attr, single, cache_name =\
         prefetcher.get_prefetch_queryset(instances, lookup.queryset)
     # We have to handle the possibility that the default manager itself added
diff --git a/tests/prefetch_related/tests.py b/tests/prefetch_related/tests.py
index 4fb71bb..a4f0bd2 100644
--- a/tests/prefetch_related/tests.py
+++ b/tests/prefetch_related/tests.py
@@ -367,6 +367,14 @@ class CustomPrefetchTests(TestCase):
         self.assertEquals(lst2[0].hlst[0].rooms_lst[1], self.room1_2)
         self.assertEquals(len(lst2[1].hlst), 0)
 
+    def test_parent_filter(self):
+        odd_pk = lambda x: x.pk % 2
+
+        houses = House.objects.prefetch_related(Prefetch('rooms', parent_filter=odd_pk))
+        for house in houses:
+            num_queries = 0 if odd_pk(house) else 1
+            with self.assertNumQueries(num_queries):
+                list(house.rooms.all())
 
 class DefaultManagerTests(TestCase):