diff --git a/django/contrib/contenttypes/generic.py b/django/contrib/contenttypes/generic.py
index c1db206515..3c36f773eb 100644
--- a/django/contrib/contenttypes/generic.py
+++ b/django/contrib/contenttypes/generic.py
@@ -39,6 +39,7 @@ class GenericForeignKey(six.with_metaclass(RenameGenericForeignKeyMethods)):
         self.ct_field = ct_field
         self.fk_field = fk_field
         self.for_concrete_model = for_concrete_model
+        self.editable = False
 
     def contribute_to_class(self, cls, name):
         self.name = name
diff --git a/django/forms/models.py b/django/forms/models.py
index c18680247d..6587be170f 100644
--- a/django/forms/models.py
+++ b/django/forms/models.py
@@ -82,7 +82,12 @@ def save_instance(form, instance, fields=None, fail_message='saved',
     # Wrap up the saving of m2m data as a function.
     def save_m2m():
         cleaned_data = form.cleaned_data
-        for f in opts.many_to_many:
+        # Note that for historical reasons we want to include also
+        # virtual_fields here. (GenericRelation was previously a fake
+        # m2m field).
+        for f in opts.many_to_many + opts.virtual_fields:
+            if not hasattr(f, 'save_form_data'):
+                continue
             if fields and f.name not in fields:
                 continue
             if exclude and f.name in exclude:
@@ -118,8 +123,8 @@ def model_to_dict(instance, fields=None, exclude=None):
     from django.db.models.fields.related import ManyToManyField
     opts = instance._meta
     data = {}
-    for f in opts.concrete_fields + opts.many_to_many:
-        if not f.editable:
+    for f in opts.concrete_fields + opts.virtual_fields + opts.many_to_many:
+        if not getattr(f, 'editable', False):
             continue
         if fields and not f.name in fields:
             continue
@@ -168,8 +173,8 @@ def fields_for_model(model, fields=None, exclude=None, widgets=None,
     field_list = []
     ignored = []
     opts = model._meta
-    for f in sorted(opts.concrete_fields + opts.many_to_many):
-        if not f.editable:
+    for f in sorted(opts.concrete_fields + opts.virtual_fields + opts.many_to_many):
+        if not getattr(f, 'editable', False):
             continue
         if fields is not None and not f.name in fields:
             continue
diff --git a/docs/releases/1.6.1.txt b/docs/releases/1.6.1.txt
index baf53e5cd3..55115704bb 100644
--- a/docs/releases/1.6.1.txt
+++ b/docs/releases/1.6.1.txt
@@ -20,3 +20,5 @@ Bug fixes
 * Fixed :class:`~django.contrib.auth.backends.ModelBackend` raising
   ``UnboundLocalError`` if :func:`~django.contrib.auth.get_user_model`
   raised an error (#21439).
+* Fixed a regression that prevented editable ``GenericRelation`` subclasses
+  from working in ``ModelForms``.
diff --git a/tests/generic_relations_regress/models.py b/tests/generic_relations_regress/models.py
index d716f09058..b504ac60f0 100644
--- a/tests/generic_relations_regress/models.py
+++ b/tests/generic_relations_regress/models.py
@@ -123,8 +123,17 @@ class Tag(models.Model):
 class Board(models.Model):
     name = models.CharField(primary_key=True, max_length=15)
 
+class SpecialGenericRelation(generic.GenericRelation):
+    def __init__(self, *args, **kwargs):
+        super(SpecialGenericRelation, self).__init__(*args, **kwargs)
+        self.editable = True
+        self.save_form_data_calls = 0
+
+    def save_form_data(self, *args, **kwargs):
+        self.save_form_data_calls += 1
+
 class HasLinks(models.Model):
-    links = generic.GenericRelation(Link)
+    links = SpecialGenericRelation(Link)
 
     class Meta:
         abstract = True
diff --git a/tests/generic_relations_regress/tests.py b/tests/generic_relations_regress/tests.py
index 75edff34f2..7b3b90b342 100644
--- a/tests/generic_relations_regress/tests.py
+++ b/tests/generic_relations_regress/tests.py
@@ -1,6 +1,7 @@
 from django.db.models import Q
 from django.db.utils import IntegrityError
 from django.test import TestCase, skipIfDBFeature
+from django.forms.models import modelform_factory
 
 from .models import (
     Address, Place, Restaurant, Link, CharLink, TextLink,
@@ -212,3 +213,13 @@ class GenericRelationTests(TestCase):
         # B would then fail).
         self.assertNotIn(" join ", str(B.objects.exclude(a__flag=True).query).lower())
         self.assertIn("content_type_id", str(B.objects.exclude(a__flag=True).query).lower())
+
+    def test_editable_generic_rel(self):
+        GenericRelationForm = modelform_factory(HasLinkThing, fields='__all__')
+        form = GenericRelationForm()
+        self.assertIn('links', form.fields)
+        form = GenericRelationForm({'links': None})
+        self.assertTrue(form.is_valid())
+        form.save()
+        links = HasLinkThing._meta.get_field_by_name('links')[0].field
+        self.assertEqual(links.save_form_data_calls, 1)