diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 4a330192f26..479a694bcac 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -979,8 +979,10 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 		int			childRTindex;
 		RangeTblEntry *childRTE;
 		RelOptInfo *childrel;
+		List	   *childrinfos;
 		ListCell   *parentvars;
 		ListCell   *childvars;
+		ListCell   *lc;
 
 		/* append_rel_list contains all append rels; ignore others */
 		if (appinfo->parent_relid != parentRTindex)
@@ -1021,6 +1023,28 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 		 * Constraint exclusion failed, so copy the parent's join quals and
 		 * targetlist to the child, with appropriate variable substitutions.
 		 *
+		 * We skip join quals that came from above outer joins that can null
+		 * this rel, since they would be of no value while generating paths
+		 * for the child.  This saves some effort while processing the child
+		 * rel, and it also avoids an implementation restriction in
+		 * adjust_appendrel_attrs (it can't apply nullingrels to a non-Var).
+		 */
+		childrinfos = NIL;
+		foreach(lc, rel->joininfo)
+		{
+			RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+			if (!bms_overlap(rinfo->clause_relids, rel->nulling_relids))
+				childrinfos = lappend(childrinfos,
+									  adjust_appendrel_attrs(root,
+															 (Node *) rinfo,
+															 1, &appinfo));
+		}
+		childrel->joininfo = childrinfos;
+
+		/*
+		 * Now for the child's targetlist.
+		 *
 		 * NB: the resulting childrel->reltarget->exprs may contain arbitrary
 		 * expressions, which otherwise would not occur in a rel's targetlist.
 		 * Code that might be looking at an appendrel child must cope with
@@ -1028,10 +1052,6 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 		 * PlaceHolderVars.)  XXX we do not bother to update the cost or width
 		 * fields of childrel->reltarget; not clear if that would be useful.
 		 */
-		childrel->joininfo = (List *)
-			adjust_appendrel_attrs(root,
-								   (Node *) rel->joininfo,
-								   1, &appinfo);
 		childrel->reltarget->exprs = (List *)
 			adjust_appendrel_attrs(root,
 								   (Node *) rel->reltarget->exprs,
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index e293de03c07..5d59ed7890f 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3613,6 +3613,28 @@ from int4_tbl t1
    One-Time Filter: false
 (3 rows)
 
+-- Test handling of qual pushdown to appendrel members with non-Var outputs
+explain (verbose, costs off)
+select * from int4_tbl left join (
+  select text 'foo' union all select text 'bar'
+) ss(x) on true
+where ss.x is null;
+               QUERY PLAN                
+-----------------------------------------
+ Nested Loop Left Join
+   Output: int4_tbl.f1, ('foo'::text)
+   Filter: (('foo'::text) IS NULL)
+   ->  Seq Scan on public.int4_tbl
+         Output: int4_tbl.f1
+   ->  Materialize
+         Output: ('foo'::text)
+         ->  Append
+               ->  Result
+                     Output: 'foo'::text
+               ->  Result
+                     Output: 'bar'::text
+(12 rows)
+
 --
 -- test inlining of immutable functions
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 5c0328ed764..a630f58b571 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1189,6 +1189,13 @@ from int4_tbl t1
               left join information_schema.column_udt_usage on null)
   on null;
 
+-- Test handling of qual pushdown to appendrel members with non-Var outputs
+explain (verbose, costs off)
+select * from int4_tbl left join (
+  select text 'foo' union all select text 'bar'
+) ss(x) on true
+where ss.x is null;
+
 --
 -- test inlining of immutable functions
 --