diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 24e93f9b28..71f746e891 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -3041,17 +3041,6 @@ The commands accepted in replication mode are:
      </para>
     </listitem>
   </varlistentry>
-
-  <varlistentry>
-    <term><literal>BASE_BACKUP</literal> [ <literal>LABEL</literal> <replaceable>'label'</replaceable> ] [ <literal>PROGRESS</literal> ] [ <literal>FAST</literal> ] [ <literal>WAL</literal> ] [ <literal>NOWAIT</literal> ] [ <literal>MAX_RATE</literal> <replaceable>rate</replaceable> ] [ <literal>TABLESPACE_MAP</literal> ] [ <literal>NOVERIFY_CHECKSUMS</literal> ] [ <literal>MANIFEST</literal> <replaceable>manifest_option</replaceable> ] [ <literal>MANIFEST_CHECKSUMS</literal> <replaceable>checksum_algorithm</replaceable> ]
-    </term>
-    <listitem>
-     <para>
-      For compatibility with older releases, this alternative syntax for
-      the <literal>BASE_BACKUP</literal> command is still supported.
-     </para>
-    </listitem>
-  </varlistentry>
 </variablelist>
 
 </para>
diff --git a/src/backend/replication/repl_gram.y b/src/backend/replication/repl_gram.y
index 3b92180e8c..ee0c0774ea 100644
--- a/src/backend/replication/repl_gram.y
+++ b/src/backend/replication/repl_gram.y
@@ -67,15 +67,7 @@ Node *replication_parse_result;
 %token K_CREATE_REPLICATION_SLOT
 %token K_DROP_REPLICATION_SLOT
 %token K_TIMELINE_HISTORY
-%token K_LABEL
-%token K_PROGRESS
-%token K_FAST
 %token K_WAIT
-%token K_NOWAIT
-%token K_MAX_RATE
-%token K_WAL
-%token K_TABLESPACE_MAP
-%token K_NOVERIFY_CHECKSUMS
 %token K_TIMELINE
 %token K_PHYSICAL
 %token K_LOGICAL
@@ -86,15 +78,13 @@ Node *replication_parse_result;
 %token K_EXPORT_SNAPSHOT
 %token K_NOEXPORT_SNAPSHOT
 %token K_USE_SNAPSHOT
-%token K_MANIFEST
-%token K_MANIFEST_CHECKSUMS
 
 %type <node>	command
 %type <node>	base_backup start_replication start_logical_replication
 				create_replication_slot drop_replication_slot identify_system
 				read_replication_slot timeline_history show
-%type <list>	base_backup_legacy_opt_list generic_option_list
-%type <defelt>	base_backup_legacy_opt generic_option
+%type <list>	generic_option_list
+%type <defelt>	generic_option
 %type <uintval>	opt_timeline
 %type <list>	plugin_options plugin_opt_list
 %type <defelt>	plugin_opt_elem
@@ -167,15 +157,7 @@ var_name:	IDENT	{ $$ = $1; }
 		;
 
 /*
- * BASE_BACKUP ( option [ 'value' ] [, ...] )
- *
- * We also still support the legacy syntax:
- *
- * BASE_BACKUP [LABEL '<label>'] [PROGRESS] [FAST] [WAL] [NOWAIT]
- * [MAX_RATE %d] [TABLESPACE_MAP] [NOVERIFY_CHECKSUMS]
- * [MANIFEST %s] [MANIFEST_CHECKSUMS %s]
- *
- * Future options should be supported only using the new syntax.
+ * BASE_BACKUP [ ( option [ 'value' ] [, ...] ) ]
  */
 base_backup:
 			K_BASE_BACKUP '(' generic_option_list ')'
@@ -184,74 +166,13 @@ base_backup:
 					cmd->options = $3;
 					$$ = (Node *) cmd;
 				}
-			| K_BASE_BACKUP base_backup_legacy_opt_list
+			| K_BASE_BACKUP
 				{
 					BaseBackupCmd *cmd = makeNode(BaseBackupCmd);
-					cmd->options = $2;
 					$$ = (Node *) cmd;
 				}
 			;
 
-base_backup_legacy_opt_list:
-			base_backup_legacy_opt_list base_backup_legacy_opt
-				{ $$ = lappend($1, $2); }
-			| /* EMPTY */
-				{ $$ = NIL; }
-			;
-
-base_backup_legacy_opt:
-			K_LABEL SCONST
-				{
-				  $$ = makeDefElem("label",
-								   (Node *)makeString($2), -1);
-				}
-			| K_PROGRESS
-				{
-				  $$ = makeDefElem("progress",
-								   (Node *)makeBoolean(true), -1);
-				}
-			| K_FAST
-				{
-				  $$ = makeDefElem("checkpoint",
-								   (Node *)makeString("fast"), -1);
-				}
-			| K_WAL
-				{
-				  $$ = makeDefElem("wal",
-								   (Node *)makeBoolean(true), -1);
-				}
-			| K_NOWAIT
-				{
-				  $$ = makeDefElem("wait",
-								   (Node *)makeBoolean(false), -1);
-				}
-			| K_MAX_RATE UCONST
-				{
-				  $$ = makeDefElem("max_rate",
-								   (Node *)makeInteger($2), -1);
-				}
-			| K_TABLESPACE_MAP
-				{
-				  $$ = makeDefElem("tablespace_map",
-								   (Node *)makeBoolean(true), -1);
-				}
-			| K_NOVERIFY_CHECKSUMS
-				{
-				  $$ = makeDefElem("verify_checksums",
-								   (Node *)makeBoolean(false), -1);
-				}
-			| K_MANIFEST SCONST
-				{
-				  $$ = makeDefElem("manifest",
-								   (Node *)makeString($2), -1);
-				}
-			| K_MANIFEST_CHECKSUMS SCONST
-				{
-				  $$ = makeDefElem("manifest_checksums",
-								   (Node *)makeString($2), -1);
-				}
-			;
-
 create_replication_slot:
 			/* CREATE_REPLICATION_SLOT slot TEMPORARY PHYSICAL [options] */
 			K_CREATE_REPLICATION_SLOT IDENT opt_temporary K_PHYSICAL create_slot_options
@@ -481,15 +402,7 @@ ident_or_keyword:
 			| K_CREATE_REPLICATION_SLOT	{ $$ = "create_replication_slot"; }
 			| K_DROP_REPLICATION_SLOT		{ $$ = "drop_replication_slot"; }
 			| K_TIMELINE_HISTORY			{ $$ = "timeline_history"; }
-			| K_LABEL						{ $$ = "label"; }
-			| K_PROGRESS					{ $$ = "progress"; }
-			| K_FAST						{ $$ = "fast"; }
 			| K_WAIT						{ $$ = "wait"; }
-			| K_NOWAIT						{ $$ = "nowait"; }
-			| K_MAX_RATE					{ $$ = "max_rate"; }
-			| K_WAL							{ $$ = "wal"; }
-			| K_TABLESPACE_MAP				{ $$ = "tablespace_map"; }
-			| K_NOVERIFY_CHECKSUMS			{ $$ = "noverify_checksums"; }
 			| K_TIMELINE					{ $$ = "timeline"; }
 			| K_PHYSICAL					{ $$ = "physical"; }
 			| K_LOGICAL						{ $$ = "logical"; }
@@ -500,8 +413,6 @@ ident_or_keyword:
 			| K_EXPORT_SNAPSHOT				{ $$ = "export_snapshot"; }
 			| K_NOEXPORT_SNAPSHOT			{ $$ = "noexport_snapshot"; }
 			| K_USE_SNAPSHOT				{ $$ = "use_snapshot"; }
-			| K_MANIFEST					{ $$ = "manifest"; }
-			| K_MANIFEST_CHECKSUMS			{ $$ = "manifest_checksums"; }
 		;
 
 %%
diff --git a/src/backend/replication/repl_scanner.l b/src/backend/replication/repl_scanner.l
index d992bcc2e3..4b64c0d768 100644
--- a/src/backend/replication/repl_scanner.l
+++ b/src/backend/replication/repl_scanner.l
@@ -108,17 +108,9 @@ identifier		{ident_start}{ident_cont}*
 %}
 
 BASE_BACKUP			{ return K_BASE_BACKUP; }
-FAST			{ return K_FAST; }
 IDENTIFY_SYSTEM		{ return K_IDENTIFY_SYSTEM; }
 READ_REPLICATION_SLOT	{ return K_READ_REPLICATION_SLOT; }
 SHOW		{ return K_SHOW; }
-LABEL			{ return K_LABEL; }
-NOWAIT			{ return K_NOWAIT; }
-PROGRESS			{ return K_PROGRESS; }
-MAX_RATE		{ return K_MAX_RATE; }
-WAL			{ return K_WAL; }
-TABLESPACE_MAP			{ return K_TABLESPACE_MAP; }
-NOVERIFY_CHECKSUMS	{ return K_NOVERIFY_CHECKSUMS; }
 TIMELINE			{ return K_TIMELINE; }
 START_REPLICATION	{ return K_START_REPLICATION; }
 CREATE_REPLICATION_SLOT		{ return K_CREATE_REPLICATION_SLOT; }
@@ -134,8 +126,6 @@ EXPORT_SNAPSHOT		{ return K_EXPORT_SNAPSHOT; }
 NOEXPORT_SNAPSHOT	{ return K_NOEXPORT_SNAPSHOT; }
 USE_SNAPSHOT		{ return K_USE_SNAPSHOT; }
 WAIT				{ return K_WAIT; }
-MANIFEST			{ return K_MANIFEST; }
-MANIFEST_CHECKSUMS	{ return K_MANIFEST_CHECKSUMS; }
 
 {space}+		{ /* do nothing */ }