diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 44a59e1d4f..0165f794b0 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -984,7 +984,8 @@ static void
 exec_simple_query(const char *query_string)
 {
 	CommandDest dest = whereToSendOutput;
-	MemoryContext oldcontext;
+	MemoryContext oldcontext,
+				  stmtcontext;
 	List	   *parsetree_list;
 	ListCell   *parsetree_item;
 	bool		save_log_statement_stats = log_statement_stats;
@@ -1132,10 +1133,14 @@ exec_simple_query(const char *query_string)
 		/*
 		 * OK to analyze, rewrite, and plan this query.
 		 *
-		 * Switch to appropriate context for constructing querytrees (again,
-		 * these must outlive the execution context).
+		 * Switch to appropriate context for constructing querytrees.
+		 * Memory allocated during this construction is released before
+		 * the generated plan is executed.
 		 */
-		oldcontext = MemoryContextSwitchTo(MessageContext);
+		stmtcontext = AllocSetContextCreate(MessageContext,
+											"statement parse/plan context",
+											ALLOCSET_DEFAULT_SIZES);
+		oldcontext = MemoryContextSwitchTo(stmtcontext);
 
 		querytree_list = pg_analyze_and_rewrite(parsetree, query_string,
 												NULL, 0, NULL);
@@ -1143,6 +1148,14 @@ exec_simple_query(const char *query_string)
 		plantree_list = pg_plan_queries(querytree_list,
 										CURSOR_OPT_PARALLEL_OK, NULL);
 
+		/*
+		 * Copy the plan trees into the longer-lived MessageContext and delete
+		 * the temporary context used to generate them.
+		 */
+		MemoryContextSwitchTo(MessageContext);
+		plantree_list = copyObject(plantree_list);
+		MemoryContextDelete(stmtcontext);
+
 		/* Done with the snapshot used for parsing/planning */
 		if (snapshot_set)
 			PopActiveSnapshot();