diff --git a/doc/src/sgml/ref/pgbench.sgml b/doc/src/sgml/ref/pgbench.sgml
index 9d18524834..24833f46bc 100644
--- a/doc/src/sgml/ref/pgbench.sgml
+++ b/doc/src/sgml/ref/pgbench.sgml
@@ -916,6 +916,8 @@ pgbench <optional> <replaceable>options</replaceable> </optional> <replaceable>d
    value can be inserted into a SQL command by writing
    <literal>:</literal><replaceable>variablename</replaceable>.  When running more than
    one client session, each session has its own set of variables.
+   <application>pgbench</application> supports up to 255 variable uses in one
+   statement.
   </para>
 
    <table id="pgbench-automatic-variables">
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 5df54a8e57..4789ab92ee 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -476,7 +476,12 @@ typedef struct
  */
 #define SQL_COMMAND		1
 #define META_COMMAND	2
-#define MAX_ARGS		10
+
+/*
+ * max number of backslash command arguments or SQL variables,
+ * including the command or SQL statement itself
+ */
+#define MAX_ARGS		256
 
 typedef enum MetaCommand
 {
@@ -4124,6 +4129,10 @@ parseQuery(Command *cmd)
 			continue;
 		}
 
+		/*
+		 * cmd->argv[0] is the SQL statement itself, so the max number of
+		 * arguments is one less than MAX_ARGS
+		 */
 		if (cmd->argc >= MAX_ARGS)
 		{
 			fprintf(stderr, "statement has too many arguments (maximum is %d): %s\n",
@@ -4461,6 +4470,10 @@ process_backslash_command(PsqlScanState sstate, const char *source)
 	/* For all other commands, collect remaining words. */
 	while (expr_lex_one_word(sstate, &word_buf, &word_offset))
 	{
+		/*
+		 * my_command->argv[0] is the command itself, so the max number of
+		 * arguments is one less than MAX_ARGS
+		 */
 		if (j >= MAX_ARGS)
 			syntax_error(source, lineno, my_command->first_line, my_command->argv[0],
 						 "too many arguments", NULL, -1);
diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index 930ff4ebb9..45888dc12e 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/src/bin/pgbench/t/001_pgbench_with_server.pl
@@ -597,11 +597,10 @@ my @errors = (
 }
 	],
 	[
-		'sql too many args', 1, [qr{statement has too many arguments.*\b9\b}],
-		q{-- MAX_ARGS=10 for prepared
+		'sql too many args', 1, [qr{statement has too many arguments.*\b255\b}],
+		q{-- MAX_ARGS=256 for prepared
 \set i 0
-SELECT LEAST(:i, :i, :i, :i, :i, :i, :i, :i, :i, :i, :i);
-}
+SELECT LEAST(}.join(', ', (':i') x 256).q{)}
 	],
 
 	# SHELL
@@ -619,25 +618,8 @@ SELECT LEAST(:i, :i, :i, :i, :i, :i, :i, :i, :i, :i, :i);
 	[ 'shell missing command', 1, [qr{missing command }], q{\shell} ],
 	[
 		'shell too many args', 1, [qr{too many arguments in command "shell"}],
-		q{-- 257 arguments to \shell
-\shell echo \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F \
- 0 1 2 3 4 5 6 7 8 9 A B C D E F
-}
+		q{-- 256 arguments to \shell
+\shell echo }.join(' ', ('arg') x 255)
 	],
 
 	# SET