diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index c913267476..1623263964 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -305,6 +305,7 @@ class Query(BaseExpression):
             obj.annotation_select_mask = None
         else:
             obj.annotation_select_mask = self.annotation_select_mask.copy()
+        obj.combined_queries = tuple(query.clone() for query in self.combined_queries)
         # _annotation_select_cache cannot be copied, as doing so breaks the
         # (necessary) state in which both annotations and
         # _annotation_select_cache point to the same underlying objects.
@@ -1777,6 +1778,8 @@ class Query(BaseExpression):
 
     def set_empty(self):
         self.where.add(NothingNode(), AND)
+        for query in self.combined_queries:
+            query.set_empty()
 
     def is_empty(self):
         return any(isinstance(c, NothingNode) for c in self.where.children)
diff --git a/tests/queries/test_qs_combinators.py b/tests/queries/test_qs_combinators.py
index 9c6fd474ca..75e2aa2f39 100644
--- a/tests/queries/test_qs_combinators.py
+++ b/tests/queries/test_qs_combinators.py
@@ -51,6 +51,13 @@ class QuerySetSetOperationTests(TestCase):
         self.assertEqual(len(list(qs1.union(qs2, all=True))), 20)
         self.assertEqual(len(list(qs1.union(qs2))), 10)
 
+    def test_union_none(self):
+        qs1 = Number.objects.filter(num__lte=1)
+        qs2 = Number.objects.filter(num__gte=8)
+        qs3 = qs1.union(qs2)
+        self.assertSequenceEqual(qs3.none(), [])
+        self.assertNumbersEqual(qs3, [0, 1, 8, 9], ordered=False)
+
     @skipUnlessDBFeature('supports_select_intersection')
     def test_intersection_with_empty_qs(self):
         qs1 = Number.objects.all()