diff --git a/package-lock.json b/package-lock.json
index ef2de62c43..fa9476cd38 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3931,6 +3931,14 @@
 						"tar-fs": "^2.0.0",
 						"unbzip2-stream": "^1.3.3",
 						"ws": "^7.2.3"
+					},
+					"dependencies": {
+						"devtools-protocol": {
+							"version": "0.0.818844",
+							"resolved": "https://registry.npmjs.org/devtools-protocol/-/devtools-protocol-0.0.818844.tgz",
+							"integrity": "sha512-AD1hi7iVJ8OD0aMLQU5VK0XH9LDlA1+BcPIgrAxPfaibx2DbWucuyOhc4oyQCbnvDDO68nN6/LcKfqTP343Jjg==",
+							"dev": true
+						}
 					}
 				},
 				"rimraf": {
@@ -8058,12 +8066,6 @@
 			"integrity": "sha512-ZIzRpLJrOj7jjP2miAtgqIfmzbxa4ZOr5jJc601zklsfEx9oTzmmj2nVpIPRpNlRTIh8lc1kyViIY7BWSGNmKw==",
 			"dev": true
 		},
-		"devtools-protocol": {
-			"version": "0.0.818844",
-			"resolved": "https://registry.npmjs.org/devtools-protocol/-/devtools-protocol-0.0.818844.tgz",
-			"integrity": "sha512-AD1hi7iVJ8OD0aMLQU5VK0XH9LDlA1+BcPIgrAxPfaibx2DbWucuyOhc4oyQCbnvDDO68nN6/LcKfqTP343Jjg==",
-			"dev": true
-		},
 		"diff": {
 			"version": "4.0.2",
 			"resolved": "https://registry.npmjs.org/diff/-/diff-4.0.2.tgz",
diff --git a/src/wp-includes/script-loader.php b/src/wp-includes/script-loader.php
index ce4c99e2ea..cde954418b 100644
--- a/src/wp-includes/script-loader.php
+++ b/src/wp-includes/script-loader.php
@@ -267,6 +267,18 @@ function wp_default_packages_scripts( $scripts ) {
 		if ( in_array( 'wp-i18n', $dependencies, true ) ) {
 			$scripts->set_translations( $handle );
 		}
+
+		// Manually set the text direction localization after wp-i18n is
+		// printed. This ensures that wp.i18n.isRTL() returns true in RTL
+		// languages. We cannot use $scripts->set_translations( 'wp-i18n' ) to
+		// do this because WordPress prints a script's translations *before*
+		// printing the script, which means, in the case of wp-i18n, that
+		// wp.i18n.setLocaleData() is called before wp.i18n is defined.
+		if ( 'wp-i18n' === $handle ) {
+			$ltr    = _x( 'ltr', 'text direction', 'default' );
+			$script = sprintf( "wp.i18n.setLocaleData( { 'text direction\u0004ltr': [ '%s' ] } );", $ltr );
+			$scripts->add_inline_script( $handle, $script, 'after' );
+		}
 	}
 }
 
diff --git a/tests/phpunit/tests/dependencies/scripts.php b/tests/phpunit/tests/dependencies/scripts.php
index cfc3540f84..2b6778954e 100644
--- a/tests/phpunit/tests/dependencies/scripts.php
+++ b/tests/phpunit/tests/dependencies/scripts.php
@@ -723,6 +723,9 @@ JS;
 		$expected .= "<script type='text/javascript' src='/wp-includes/js/dist/dom-ready{$suffix}.js' id='wp-dom-ready-js'></script>\n";
 		$expected .= "<script type='text/javascript' src='/wp-includes/js/dist/hooks{$suffix}.js' id='wp-hooks-js'></script>\n";
 		$expected .= "<script type='text/javascript' src='/wp-includes/js/dist/i18n{$suffix}.js' id='wp-i18n-js'></script>\n";
+		$expected .= "<script type='text/javascript' id='wp-i18n-js-after'>\n";
+		$expected .= "wp.i18n.setLocaleData( { 'text direction\u0004ltr': [ 'ltr' ] } );\n";
+		$expected .= "</script>\n";
 		$expected .= "<script type='text/javascript' id='wp-a11y-js-translations'>\n";
 		$expected .= "( function( domain, translations ) {\n";
 		$expected .= "	var localeData = translations.locale_data[ domain ] || translations.locale_data.messages;\n";