diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 1dbf0ffff9e..9a1c0992bfe 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -1335,8 +1335,18 @@ ExecInsert(ModifyTableContext *context,
 	if (resultRelInfo->ri_WithCheckOptions != NIL)
 		ExecWithCheckOptions(WCO_VIEW_CHECK, resultRelInfo, slot, estate);
 
-	/* Process RETURNING if present */
-	if (resultRelInfo->ri_projectReturning)
+	/*
+	 * Process RETURNING if present.
+	 *
+	 * If this is an UPDATE/DELETE ... FOR PORTION OF, we do not return the
+	 * leftover rows inserted by ExecForPortionOfLeftovers().  Note that we
+	 * must check mtstate->operation here, because we *do* want to process the
+	 * newly inserted row of a cross-partition UPDATE with a FOR PORTION OF
+	 * clause (ExecCrossPartitionUpdate() leaves mtstate->operation set to
+	 * CMD_UPDATE, whereas ExecForPortionOfLeftovers() sets it to CMD_INSERT).
+	 */
+	if (resultRelInfo->ri_projectReturning &&
+		!(node->forPortionOf && mtstate->operation == CMD_INSERT))
 	{
 		TupleTableSlot *oldSlot = NULL;
 
diff --git a/src/test/regress/expected/for_portion_of.out b/src/test/regress/expected/for_portion_of.out
index 3c592f90e70..a6cb1ba8380 100644
--- a/src/test/regress/expected/for_portion_of.out
+++ b/src/test/regress/expected/for_portion_of.out
@@ -920,14 +920,23 @@ SELECT * FROM for_portion_of_test ORDER BY id, valid_at;
 \set QUIET true
 -- UPDATE ... RETURNING returns only the updated values
 -- (not the inserted side values, which are added by a separate "statement"):
+CREATE FUNCTION fpo_returning_row(text)
+RETURNS text LANGUAGE plpgsql AS
+$$
+BEGIN
+  RAISE NOTICE 'RETURNING %', $1;
+  RETURN $1;
+END;
+$$;
 UPDATE for_portion_of_test
   FOR PORTION OF valid_at FROM '2018-02-01' TO '2018-02-15'
   SET name = 'three^3'
   WHERE id = '[3,4)'
-  RETURNING *;
-  id   |        valid_at         |  name   
--------+-------------------------+---------
- [3,4) | [2018-02-01,2018-02-15) | three^3
+  RETURNING *, fpo_returning_row(for_portion_of_test::text);
+NOTICE:  RETURNING ("[3,4)","[2018-02-01,2018-02-15)",three^3)
+  id   |        valid_at         |  name   |              fpo_returning_row              
+-------+-------------------------+---------+---------------------------------------------
+ [3,4) | [2018-02-01,2018-02-15) | three^3 | ("[3,4)","[2018-02-01,2018-02-15)",three^3)
 (1 row)
 
 -- UPDATE ... RETURNING supports NEW and OLD valid_at
@@ -975,10 +984,11 @@ DELETE FROM for_portion_of_test WHERE id = '[99,100)';
 DELETE FROM for_portion_of_test
   FOR PORTION OF valid_at FROM '2018-02-02' TO '2018-02-03'
   WHERE id = '[3,4)'
-  RETURNING *;
-  id   |        valid_at         |  name   
--------+-------------------------+---------
- [3,4) | [2018-02-01,2018-02-10) | three^3
+  RETURNING *, fpo_returning_row(for_portion_of_test::text);
+NOTICE:  RETURNING ("[3,4)","[2018-02-01,2018-02-10)",three^3)
+  id   |        valid_at         |  name   |              fpo_returning_row              
+-------+-------------------------+---------+---------------------------------------------
+ [3,4) | [2018-02-01,2018-02-10) | three^3 | ("[3,4)","[2018-02-01,2018-02-10)",three^3)
 (1 row)
 
 -- DELETE FOR PORTION OF in a PL/pgSQL function
@@ -2137,7 +2147,14 @@ UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-03-01' TO '2000-0
 UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-06-01' TO '2000-07-01'
   SET name = 'one^2',
       id = '[4,5)'
-  WHERE id = '[1,2)';
+  WHERE id = '[1,2)'
+  RETURNING id, valid_at, name, fpo_returning_row(temporal_partitioned::text);
+NOTICE:  RETURNING ("[4,5)","[2000-06-01,2000-07-01)",one^2,30)
+  id   |        valid_at         | name  |              fpo_returning_row               
+-------+-------------------------+-------+----------------------------------------------
+ [4,5) | [2000-06-01,2000-07-01) | one^2 | ("[4,5)","[2000-06-01,2000-07-01)",one^2,30)
+(1 row)
+
 -- Move from partition 3 to partition 1
 UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-06-01' TO '2000-07-01'
   SET name = 'three^2',
@@ -2199,6 +2216,7 @@ SELECT * FROM temporal_partitioned_5 ORDER BY id, valid_at;
  five   | [2000-07-01,2010-01-01) | [5,6) |      3471
 (4 rows)
 
+DROP FUNCTION fpo_returning_row;
 DROP TABLE temporal_partitioned;
 -- UPDATE/DELETE FOR PORTION OF with RULEs
 CREATE TABLE fpo_rule (f1 bigint, f2 int4range);
diff --git a/src/test/regress/sql/for_portion_of.sql b/src/test/regress/sql/for_portion_of.sql
index 5f7b04fdf6b..955cf666d66 100644
--- a/src/test/regress/sql/for_portion_of.sql
+++ b/src/test/regress/sql/for_portion_of.sql
@@ -590,11 +590,19 @@ SELECT * FROM for_portion_of_test ORDER BY id, valid_at;
 
 -- UPDATE ... RETURNING returns only the updated values
 -- (not the inserted side values, which are added by a separate "statement"):
+CREATE FUNCTION fpo_returning_row(text)
+RETURNS text LANGUAGE plpgsql AS
+$$
+BEGIN
+  RAISE NOTICE 'RETURNING %', $1;
+  RETURN $1;
+END;
+$$;
 UPDATE for_portion_of_test
   FOR PORTION OF valid_at FROM '2018-02-01' TO '2018-02-15'
   SET name = 'three^3'
   WHERE id = '[3,4)'
-  RETURNING *;
+  RETURNING *, fpo_returning_row(for_portion_of_test::text);
 
 -- UPDATE ... RETURNING supports NEW and OLD valid_at
 UPDATE for_portion_of_test
@@ -629,7 +637,7 @@ DELETE FROM for_portion_of_test WHERE id = '[99,100)';
 DELETE FROM for_portion_of_test
   FOR PORTION OF valid_at FROM '2018-02-02' TO '2018-02-03'
   WHERE id = '[3,4)'
-  RETURNING *;
+  RETURNING *, fpo_returning_row(for_portion_of_test::text);
 
 -- DELETE FOR PORTION OF in a PL/pgSQL function
 INSERT INTO for_portion_of_test (id, valid_at, name) VALUES
@@ -1439,7 +1447,8 @@ UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-03-01' TO '2000-0
 UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-06-01' TO '2000-07-01'
   SET name = 'one^2',
       id = '[4,5)'
-  WHERE id = '[1,2)';
+  WHERE id = '[1,2)'
+  RETURNING id, valid_at, name, fpo_returning_row(temporal_partitioned::text);
 
 -- Move from partition 3 to partition 1
 UPDATE temporal_partitioned FOR PORTION OF valid_at FROM '2000-06-01' TO '2000-07-01'
@@ -1460,6 +1469,7 @@ SELECT * FROM temporal_partitioned_1 ORDER BY id, valid_at;
 SELECT * FROM temporal_partitioned_3 ORDER BY id, valid_at;
 SELECT * FROM temporal_partitioned_5 ORDER BY id, valid_at;
 
+DROP FUNCTION fpo_returning_row;
 DROP TABLE temporal_partitioned;
 
 -- UPDATE/DELETE FOR PORTION OF with RULEs