diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 2feab2184f..a3f94be1d6 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -1640,13 +1640,15 @@ try_partitionwise_join(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
 											   child_rel1->relids,
 											   child_rel2->relids);
 
-		/* Build correct join relids for child join */
-		child_joinrelids = bms_union(child_rel1->relids, child_rel2->relids);
-		child_joinrelids = add_outer_joins_to_relids(root, child_joinrelids,
-													 child_sjinfo, NULL);
-
 		/* Find the AppendRelInfo structures */
-		appinfos = find_appinfos_by_relids(root, child_joinrelids, &nappinfos);
+		appinfos = find_appinfos_by_relids(root,
+										   bms_union(child_rel1->relids,
+													 child_rel2->relids),
+										   &nappinfos);
+
+		/* Build correct join relids for child join */
+		child_joinrelids = adjust_child_relids(joinrel->relids,
+											   nappinfos, appinfos);
 
 		/*
 		 * Construct restrictions applicable to the child join from those
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 15e3910b79..76dad17e33 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -871,10 +871,19 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,
 	/* The parent joinrel should have consider_partitionwise_join set. */
 	Assert(parent_joinrel->consider_partitionwise_join);
 
+	/*
+	 * Find the AppendRelInfo structures for the child baserels.  We'll need
+	 * these for computing the child join's relid set, and later for mapping
+	 * Vars to the child rel.
+	 */
+	appinfos = find_appinfos_by_relids(root,
+									   bms_union(outer_rel->relids,
+												 inner_rel->relids),
+									   &nappinfos);
+
 	joinrel->reloptkind = RELOPT_OTHER_JOINREL;
-	joinrel->relids = bms_union(outer_rel->relids, inner_rel->relids);
-	joinrel->relids = add_outer_joins_to_relids(root, joinrel->relids, sjinfo,
-												NULL);
+	joinrel->relids = adjust_child_relids(parent_joinrel->relids,
+										  nappinfos, appinfos);
 	joinrel->rows = 0;
 	/* cheap startup cost is interesting iff not all tuples to be retrieved */
 	joinrel->consider_startup = (root->tuple_fraction > 0);
@@ -935,9 +944,6 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,
 	/* Compute information relevant to foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);
 
-	/* Compute information needed for mapping Vars to the child rel */
-	appinfos = find_appinfos_by_relids(root, joinrel->relids, &nappinfos);
-
 	/* Set up reltarget struct */
 	build_child_join_reltarget(root, parent_joinrel, joinrel,
 							   nappinfos, appinfos);
diff --git a/src/test/regress/expected/partition_join.out b/src/test/regress/expected/partition_join.out
index 762cc8e53b..6560fe2416 100644
--- a/src/test/regress/expected/partition_join.out
+++ b/src/test/regress/expected/partition_join.out
@@ -62,6 +62,52 @@ SELECT t1.a, t1.c, t2.b, t2.c FROM prt1 t1, prt2 t2 WHERE t1.a = t2.b AND t1.b =
  450 | 0450 | 450 | 0450
 (4 rows)
 
+-- left outer join, 3-way
+EXPLAIN (COSTS OFF)
+SELECT COUNT(*) FROM prt1 t1
+  LEFT JOIN prt1 t2 ON t1.a = t2.a
+  LEFT JOIN prt1 t3 ON t2.a = t3.a;
+                       QUERY PLAN                       
+--------------------------------------------------------
+ Aggregate
+   ->  Append
+         ->  Hash Left Join
+               Hash Cond: (t2_1.a = t3_1.a)
+               ->  Hash Left Join
+                     Hash Cond: (t1_1.a = t2_1.a)
+                     ->  Seq Scan on prt1_p1 t1_1
+                     ->  Hash
+                           ->  Seq Scan on prt1_p1 t2_1
+               ->  Hash
+                     ->  Seq Scan on prt1_p1 t3_1
+         ->  Hash Left Join
+               Hash Cond: (t2_2.a = t3_2.a)
+               ->  Hash Left Join
+                     Hash Cond: (t1_2.a = t2_2.a)
+                     ->  Seq Scan on prt1_p2 t1_2
+                     ->  Hash
+                           ->  Seq Scan on prt1_p2 t2_2
+               ->  Hash
+                     ->  Seq Scan on prt1_p2 t3_2
+         ->  Hash Left Join
+               Hash Cond: (t2_3.a = t3_3.a)
+               ->  Hash Left Join
+                     Hash Cond: (t1_3.a = t2_3.a)
+                     ->  Seq Scan on prt1_p3 t1_3
+                     ->  Hash
+                           ->  Seq Scan on prt1_p3 t2_3
+               ->  Hash
+                     ->  Seq Scan on prt1_p3 t3_3
+(29 rows)
+
+SELECT COUNT(*) FROM prt1 t1
+  LEFT JOIN prt1 t2 ON t1.a = t2.a
+  LEFT JOIN prt1 t3 ON t2.a = t3.a;
+ count 
+-------
+   300
+(1 row)
+
 -- left outer join, with whole-row reference; partitionwise join does not apply
 EXPLAIN (COSTS OFF)
 SELECT t1, t2 FROM prt1 t1 LEFT JOIN prt2 t2 ON t1.a = t2.b WHERE t1.b = 0 ORDER BY t1.a, t2.b;
diff --git a/src/test/regress/sql/partition_join.sql b/src/test/regress/sql/partition_join.sql
index 9e16f1ca55..48daf3aee3 100644
--- a/src/test/regress/sql/partition_join.sql
+++ b/src/test/regress/sql/partition_join.sql
@@ -34,6 +34,15 @@ EXPLAIN (COSTS OFF)
 SELECT t1.a, t1.c, t2.b, t2.c FROM prt1 t1, prt2 t2 WHERE t1.a = t2.b AND t1.b = 0 ORDER BY t1.a, t2.b;
 SELECT t1.a, t1.c, t2.b, t2.c FROM prt1 t1, prt2 t2 WHERE t1.a = t2.b AND t1.b = 0 ORDER BY t1.a, t2.b;
 
+-- left outer join, 3-way
+EXPLAIN (COSTS OFF)
+SELECT COUNT(*) FROM prt1 t1
+  LEFT JOIN prt1 t2 ON t1.a = t2.a
+  LEFT JOIN prt1 t3 ON t2.a = t3.a;
+SELECT COUNT(*) FROM prt1 t1
+  LEFT JOIN prt1 t2 ON t1.a = t2.a
+  LEFT JOIN prt1 t3 ON t2.a = t3.a;
+
 -- left outer join, with whole-row reference; partitionwise join does not apply
 EXPLAIN (COSTS OFF)
 SELECT t1, t2 FROM prt1 t1 LEFT JOIN prt2 t2 ON t1.a = t2.b WHERE t1.b = 0 ORDER BY t1.a, t2.b;