diff --git a/django/db/models/query.py b/django/db/models/query.py
index 6a6fd82b18..cafec42697 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -246,6 +246,13 @@ class _QuerySet(object):
     # PUBLIC METHODS THAT ALTER ATTRIBUTES AND RETURN A NEW QUERYSET #
     ##################################################################
 
+    def all(self):
+        """
+        Returns a new QuerySet that is a copy of the current one. This allows a
+        QuerySet to proxy for a model manager in some cases.
+        """
+        return self._clone()
+
     def filter(self, *args, **kwargs):
         """
         Returns a new QuerySet instance with the args ANDed to the existing
diff --git a/docs/db-api.txt b/docs/db-api.txt
index 6e121b8f3d..9fc82add4a 100644
--- a/docs/db-api.txt
+++ b/docs/db-api.txt
@@ -681,6 +681,17 @@ Examples::
     >>> Entry.objects.none()
     []
 
+``all()``
+~~~~~~~~~~
+
+**New in Django development version**
+
+Returns a ''copy'' of the current ``QuerySet`` (or ``QuerySet`` subclass you
+pass in). This can be useful in some situations where you might want to pass
+in either a model manager or a ``QuerySet`` and do further filtering on the
+result. You can safely call ``all()`` on either object and then you'll
+definitely have a ``QuerySet`` to work with.
+
 ``select_related()``
 ~~~~~~~~~~~~~~~~~~~~
 
diff --git a/tests/regressiontests/queries/models.py b/tests/regressiontests/queries/models.py
index eb8595ecab..0a7ae286b7 100644
--- a/tests/regressiontests/queries/models.py
+++ b/tests/regressiontests/queries/models.py
@@ -374,5 +374,10 @@ upper bound.
 >>> X.objects.select_related()
 []
 
+Bug #3739
+The all() method on querysets returns a copy of the queryset.
+>>> q1 = Item.objects.order_by('name')
+>>> id(q1) == id(q1.all())
+False
 """}