diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 2d7e1d84d0..7422cc6983 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -24,6 +24,7 @@
 #include "catalog/pg_operator.h"
 #include "catalog/pg_proc.h"
 #include "foreign/fdwapi.h"
+#include "miscadmin.h"
 #include "nodes/makefuncs.h"
 #include "nodes/nodeFuncs.h"
 #ifdef OPTIMIZER_DEBUG
@@ -867,6 +868,9 @@ set_append_rel_size(PlannerInfo *root, RelOptInfo *rel,
 	int			nattrs;
 	ListCell   *l;
 
+	/* Guard against stack overflow due to overly deep inheritance tree. */
+	check_stack_depth();
+
 	Assert(IS_SIMPLE_REL(rel));
 
 	/*
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 987c20ac9f..ad81f0f82f 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -15,6 +15,7 @@
 #include "postgres.h"
 
 #include "catalog/pg_type.h"
+#include "catalog/pg_class.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
@@ -629,11 +630,28 @@ create_lateral_join_info(PlannerInfo *root)
 	for (rti = 1; rti < root->simple_rel_array_size; rti++)
 	{
 		RelOptInfo *brel = root->simple_rel_array[rti];
+		RangeTblEntry *brte = root->simple_rte_array[rti];
 
-		if (brel == NULL || brel->reloptkind != RELOPT_BASEREL)
+		if (brel == NULL)
+			continue;
+
+		/*
+		 * In the case of table inheritance, the parent RTE is directly linked
+		 * to every child table via an AppendRelInfo.  In the case of table
+		 * partitioning, the inheritance hierarchy is expanded one level at a
+		 * time rather than flattened.  Therefore, an other member rel that is
+		 * a partitioned table may have children of its own, and must
+		 * therefore be marked with the appropriate lateral info so that those
+		 * children eventually get marked also.
+		 */
+		Assert(IS_SIMPLE_REL(brel));
+		Assert(brte);
+		if (brel->reloptkind == RELOPT_OTHER_MEMBER_REL &&
+			(brte->rtekind != RTE_RELATION ||
+			 brte->relkind != RELKIND_PARTITIONED_TABLE))
 			continue;
 
-		if (root->simple_rte_array[rti]->inh)
+		if (brte->inh)
 		{
 			foreach(lc, root->append_rel_list)
 			{
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 6b79b3ad99..82b722b47b 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1038,7 +1038,7 @@ static void
 inheritance_planner(PlannerInfo *root)
 {
 	Query	   *parse = root->parse;
-	int			parentRTindex = parse->resultRelation;
+	int			top_parentRTindex = parse->resultRelation;
 	Bitmapset  *subqueryRTindexes;
 	Bitmapset  *modifiableARIindexes;
 	int			nominalRelation = -1;
@@ -1056,6 +1056,10 @@ inheritance_planner(PlannerInfo *root)
 	Index		rti;
 	RangeTblEntry *parent_rte;
 	List	   *partitioned_rels = NIL;
+	PlannerInfo *parent_root;
+	Query	   *parent_parse;
+	Bitmapset  *parent_relids = bms_make_singleton(top_parentRTindex);
+	PlannerInfo **parent_roots = NULL;
 
 	Assert(parse->commandType != CMD_INSERT);
 
@@ -1121,9 +1125,22 @@ inheritance_planner(PlannerInfo *root)
 	 * opposite in the case of non-partitioned inheritance parent as described
 	 * below.
 	 */
-	parent_rte = rt_fetch(parentRTindex, root->parse->rtable);
+	parent_rte = rt_fetch(top_parentRTindex, root->parse->rtable);
 	if (parent_rte->relkind == RELKIND_PARTITIONED_TABLE)
-		nominalRelation = parentRTindex;
+		nominalRelation = top_parentRTindex;
+
+	/*
+	 * The PlannerInfo for each child is obtained by translating the relevant
+	 * members of the PlannerInfo for its immediate parent, which we find
+	 * using the parent_relid in its AppendRelInfo.  We save the PlannerInfo
+	 * for each parent in an array indexed by relid for fast retrieval. Since
+	 * the maximum number of parents is limited by the number of RTEs in the
+	 * query, we use that number to allocate the array. An extra entry is
+	 * needed since relids start from 1.
+	 */
+	parent_roots = (PlannerInfo **) palloc0((list_length(parse->rtable) + 1) *
+											sizeof(PlannerInfo *));
+	parent_roots[top_parentRTindex] = root;
 
 	/*
 	 * And now we can get on with generating a plan for each child table.
@@ -1137,15 +1154,24 @@ inheritance_planner(PlannerInfo *root)
 		Path	   *subpath;
 
 		/* append_rel_list contains all append rels; ignore others */
-		if (appinfo->parent_relid != parentRTindex)
+		if (!bms_is_member(appinfo->parent_relid, parent_relids))
 			continue;
 
 		/*
+		 * expand_inherited_rtentry() always processes a parent before any of
+		 * that parent's children, so the parent_root for this relation should
+		 * already be available.
+		 */
+		parent_root = parent_roots[appinfo->parent_relid];
+		Assert(parent_root != NULL);
+		parent_parse = parent_root->parse;
+
+		/*
 		 * We need a working copy of the PlannerInfo so that we can control
 		 * propagation of information back to the main copy.
 		 */
 		subroot = makeNode(PlannerInfo);
-		memcpy(subroot, root, sizeof(PlannerInfo));
+		memcpy(subroot, parent_root, sizeof(PlannerInfo));
 
 		/*
 		 * Generate modified query with this rel as target.  We first apply
@@ -1154,15 +1180,15 @@ inheritance_planner(PlannerInfo *root)
 		 * then fool around with subquery RTEs.
 		 */
 		subroot->parse = (Query *)
-			adjust_appendrel_attrs(root,
-								   (Node *) parse,
+			adjust_appendrel_attrs(parent_root,
+								   (Node *) parent_parse,
 								   1, &appinfo);
 
 		/*
 		 * If there are securityQuals attached to the parent, move them to the
 		 * child rel (they've already been transformed properly for that).
 		 */
-		parent_rte = rt_fetch(parentRTindex, subroot->parse->rtable);
+		parent_rte = rt_fetch(appinfo->parent_relid, subroot->parse->rtable);
 		child_rte = rt_fetch(appinfo->child_relid, subroot->parse->rtable);
 		child_rte->securityQuals = parent_rte->securityQuals;
 		parent_rte->securityQuals = NIL;
@@ -1173,7 +1199,7 @@ inheritance_planner(PlannerInfo *root)
 		 * executor doesn't need to see the modified copies --- we can just
 		 * pass it the original rowMarks list.)
 		 */
-		subroot->rowMarks = copyObject(root->rowMarks);
+		subroot->rowMarks = copyObject(parent_root->rowMarks);
 
 		/*
 		 * The append_rel_list likewise might contain references to subquery
@@ -1190,7 +1216,7 @@ inheritance_planner(PlannerInfo *root)
 			ListCell   *lc2;
 
 			subroot->append_rel_list = NIL;
-			foreach(lc2, root->append_rel_list)
+			foreach(lc2, parent_root->append_rel_list)
 			{
 				AppendRelInfo *appinfo2 = lfirst_node(AppendRelInfo, lc2);
 
@@ -1225,7 +1251,7 @@ inheritance_planner(PlannerInfo *root)
 			ListCell   *lr;
 
 			rti = 1;
-			foreach(lr, parse->rtable)
+			foreach(lr, parent_parse->rtable)
 			{
 				RangeTblEntry *rte = lfirst_node(RangeTblEntry, lr);
 
@@ -1272,6 +1298,22 @@ inheritance_planner(PlannerInfo *root)
 		/* hack to mark target relation as an inheritance partition */
 		subroot->hasInheritedTarget = true;
 
+		/*
+		 * If the child is further partitioned, remember it as a parent. Since
+		 * a partitioned table does not have any data, we don't need to create
+		 * a plan for it. We do, however, need to remember the PlannerInfo for
+		 * use when processing its children.
+		 */
+		if (child_rte->inh)
+		{
+			Assert(child_rte->relkind == RELKIND_PARTITIONED_TABLE);
+			parent_relids =
+				bms_add_member(parent_relids, appinfo->child_relid);
+			parent_roots[appinfo->child_relid] = subroot;
+
+			continue;
+		}
+
 		/* Generate Path(s) for accessing this result relation */
 		grouping_planner(subroot, true, 0.0 /* retrieve all tuples */ );
 
@@ -1370,7 +1412,7 @@ inheritance_planner(PlannerInfo *root)
 
 	if (parent_rte->relkind == RELKIND_PARTITIONED_TABLE)
 	{
-		partitioned_rels = get_partitioned_child_rels(root, parentRTindex);
+		partitioned_rels = get_partitioned_child_rels(root, top_parentRTindex);
 		/* The root partitioned table is included as a child rel */
 		Assert(list_length(partitioned_rels) >= 1);
 	}
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index ccf21453fd..131f597632 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -1348,9 +1348,9 @@ expand_inherited_tables(PlannerInfo *root)
 	ListCell   *rl;
 
 	/*
-	 * expand_inherited_rtentry may add RTEs to parse->rtable; there is no
-	 * need to scan them since they can't have inh=true.  So just scan as far
-	 * as the original end of the rtable list.
+	 * expand_inherited_rtentry may add RTEs to parse->rtable. The function is
+	 * expected to recursively handle any RTEs that it creates with inh=true.
+	 * So just scan as far as the original end of the rtable list.
 	 */
 	nrtes = list_length(root->parse->rtable);
 	rl = list_head(root->parse->rtable);
@@ -1649,17 +1649,25 @@ expand_single_inheritance_child(PlannerInfo *root, RangeTblEntry *parentrte,
 	childrte = copyObject(parentrte);
 	childrte->relid = childOID;
 	childrte->relkind = childrel->rd_rel->relkind;
-	childrte->inh = false;
+	/* A partitioned child will need to be expanded further. */
+	if (childOID != parentOID &&
+		childrte->relkind == RELKIND_PARTITIONED_TABLE)
+		childrte->inh = true;
+	else
+		childrte->inh = false;
 	childrte->requiredPerms = 0;
 	childrte->securityQuals = NIL;
 	parse->rtable = lappend(parse->rtable, childrte);
 	childRTindex = list_length(parse->rtable);
 
 	/*
-	 * Build an AppendRelInfo for this parent and child, unless the child is a
-	 * partitioned table.
+	 * We need an AppendRelInfo if paths will be built for the child RTE.
+	 * If childrte->inh is true, then we'll always need to generate append
+	 * paths for it.  If childrte->inh is false, we must scan it if it's
+	 * not a partitioned table; but if it is a partitioned table, then it
+	 * never has any data of its own and need not be scanned.
 	 */
-	if (childrte->relkind != RELKIND_PARTITIONED_TABLE)
+	if (childrte->relkind != RELKIND_PARTITIONED_TABLE || childrte->inh)
 	{
 		/* Remember if we saw a real child. */
 		if (childOID != parentOID)
@@ -1694,7 +1702,12 @@ expand_single_inheritance_child(PlannerInfo *root, RangeTblEntry *parentrte,
 														appinfo->translated_vars);
 		}
 	}
-	else
+
+	/*
+	 * If this is a partitioned table, it won't be scanned; add it to the
+	 * list of partitioned child relations so that it gets properly locked.
+	 */
+	if (childrte->relkind == RELKIND_PARTITIONED_TABLE)
 		*partitioned_child_rels = lappend_int(*partitioned_child_rels,
 											  childRTindex);
 
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index a39e59d8ac..d50ff55681 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1935,10 +1935,10 @@ typedef struct SpecialJoinInfo
  *
  * When we expand an inheritable table or a UNION-ALL subselect into an
  * "append relation" (essentially, a list of child RTEs), we build an
- * AppendRelInfo for each non-partitioned child RTE.  The list of
- * AppendRelInfos indicates which child RTEs must be included when expanding
- * the parent, and each node carries information needed to translate Vars
- * referencing the parent into Vars referencing that child.
+ * AppendRelInfo for each child RTE.  The list of AppendRelInfos indicates
+ * which child RTEs must be included when expanding the parent, and each node
+ * carries information needed to translate Vars referencing the parent into
+ * Vars referencing that child.
  *
  * These structs are kept in the PlannerInfo node's append_rel_list.
  * Note that we just throw all the structs into one list, and scan the
diff --git a/src/test/regress/expected/inherit.out b/src/test/regress/expected/inherit.out
index 1fa9650ec9..2fb0b4d86e 100644
--- a/src/test/regress/expected/inherit.out
+++ b/src/test/regress/expected/inherit.out
@@ -625,6 +625,28 @@ select tableoid::regclass::text as relname, parted_tab.* from parted_tab order b
 (3 rows)
 
 drop table parted_tab;
+-- Check UPDATE with multi-level partitioned inherited target
+create table mlparted_tab (a int, b char, c text) partition by list (a);
+create table mlparted_tab_part1 partition of mlparted_tab for values in (1);
+create table mlparted_tab_part2 partition of mlparted_tab for values in (2) partition by list (b);
+create table mlparted_tab_part3 partition of mlparted_tab for values in (3);
+create table mlparted_tab_part2a partition of mlparted_tab_part2 for values in ('a');
+create table mlparted_tab_part2b partition of mlparted_tab_part2 for values in ('b');
+insert into mlparted_tab values (1, 'a'), (2, 'a'), (2, 'b'), (3, 'a');
+update mlparted_tab mlp set c = 'xxx'
+from
+  (select a from some_tab union all select a+1 from some_tab) ss (a)
+where (mlp.a = ss.a and mlp.b = 'b') or mlp.a = 3;
+select tableoid::regclass::text as relname, mlparted_tab.* from mlparted_tab order by 1,2;
+       relname       | a | b |  c  
+---------------------+---+---+-----
+ mlparted_tab_part1  | 1 | a | 
+ mlparted_tab_part2a | 2 | a | 
+ mlparted_tab_part2b | 2 | b | xxx
+ mlparted_tab_part3  | 3 | a | xxx
+(4 rows)
+
+drop table mlparted_tab;
 drop table some_tab cascade;
 NOTICE:  drop cascades to table some_tab_child
 /* Test multiple inheritance of column defaults */
diff --git a/src/test/regress/sql/inherit.sql b/src/test/regress/sql/inherit.sql
index c96580cd81..01780d4977 100644
--- a/src/test/regress/sql/inherit.sql
+++ b/src/test/regress/sql/inherit.sql
@@ -154,6 +154,23 @@ where parted_tab.a = ss.a;
 select tableoid::regclass::text as relname, parted_tab.* from parted_tab order by 1,2;
 
 drop table parted_tab;
+
+-- Check UPDATE with multi-level partitioned inherited target
+create table mlparted_tab (a int, b char, c text) partition by list (a);
+create table mlparted_tab_part1 partition of mlparted_tab for values in (1);
+create table mlparted_tab_part2 partition of mlparted_tab for values in (2) partition by list (b);
+create table mlparted_tab_part3 partition of mlparted_tab for values in (3);
+create table mlparted_tab_part2a partition of mlparted_tab_part2 for values in ('a');
+create table mlparted_tab_part2b partition of mlparted_tab_part2 for values in ('b');
+insert into mlparted_tab values (1, 'a'), (2, 'a'), (2, 'b'), (3, 'a');
+
+update mlparted_tab mlp set c = 'xxx'
+from
+  (select a from some_tab union all select a+1 from some_tab) ss (a)
+where (mlp.a = ss.a and mlp.b = 'b') or mlp.a = 3;
+select tableoid::regclass::text as relname, mlparted_tab.* from mlparted_tab order by 1,2;
+
+drop table mlparted_tab;
 drop table some_tab cascade;
 
 /* Test multiple inheritance of column defaults */