diff --git a/wp-includes/class-wp-textdomain-registry.php b/wp-includes/class-wp-textdomain-registry.php
index b66b5b18a6..b2cbd72fa5 100644
--- a/wp-includes/class-wp-textdomain-registry.php
+++ b/wp-includes/class-wp-textdomain-registry.php
@@ -150,21 +150,21 @@ class WP_Textdomain_Registry {
 	}
 
 	/**
-	 * Retrieves .mo files from the specified path.
+	 * Retrieves translation files from the specified path.
 	 *
 	 * Allows early retrieval through the {@see 'pre_get_mo_files_from_path'} filter to optimize
 	 * performance, especially in directories with many files.
 	 *
 	 * @since 6.5.0
 	 *
-	 * @param string $path The directory path to search for .mo files.
-	 * @return array Array of .mo file paths.
+	 * @param string $path The directory path to search for translation files.
+	 * @return array Array of translation file paths. Can contain .mo and .l10n.php files.
 	 */
 	public function get_language_files_from_path( $path ) {
 		$path = rtrim( $path, '/' ) . '/';
 
 		/**
-		 * Filters the .mo files retrieved from a specified path before the actual lookup.
+		 * Filters the translation files retrieved from a specified path before the actual lookup.
 		 *
 		 * Returning a non-null value from the filter will effectively short-circuit
 		 * the MO files lookup, returning that value instead.
@@ -174,27 +174,33 @@ class WP_Textdomain_Registry {
 		 *
 		 * @since 6.5.0
 		 *
-		 * @param null|array $mo_files List of .mo files. Default null.
-		 * @param string $path The path from which .mo files are being fetched.
+		 * @param null|array $files List of translation files. Default null.
+		 * @param string $path The path from which translation files are being fetched.
 		 **/
-		$mo_files = apply_filters( 'pre_get_language_files_from_path', null, $path );
+		$files = apply_filters( 'pre_get_language_files_from_path', null, $path );
 
-		if ( null !== $mo_files ) {
-			return $mo_files;
+		if ( null !== $files ) {
+			return $files;
 		}
 
 		$cache_key = 'cached_mo_files_' . md5( $path );
-		$mo_files  = wp_cache_get( $cache_key, 'translations' );
+		$files     = wp_cache_get( $cache_key, 'translations' );
 
-		if ( false === $mo_files ) {
-			$mo_files = glob( $path . '*.mo' );
-			if ( false === $mo_files ) {
-				$mo_files = array();
+		if ( false === $files ) {
+			$files = glob( $path . '*.mo' );
+			if ( false === $files ) {
+				$files = array();
 			}
-			wp_cache_set( $cache_key, $mo_files, 'translations' );
+
+			$php_files = glob( $path . '*.l10n.php' );
+			if ( is_array( $php_files ) ) {
+				$files = array_merge( $files, $php_files );
+			}
+
+			wp_cache_set( $cache_key, $files, 'translations' );
 		}
 
-		return $mo_files;
+		return $files;
 	}
 
 	/**
@@ -295,17 +301,18 @@ class WP_Textdomain_Registry {
 		foreach ( $locations as $location ) {
 			$files = $this->get_language_files_from_path( $location );
 
-			$path = "$location/$domain-$locale.mo";
+			$mo_path  = "$location/$domain-$locale.mo";
+			$php_path = "$location/$domain-$locale.l10n.php";
 
-			foreach ( $files as $mo_path ) {
+			foreach ( $files as $file_path ) {
 				if (
 					! in_array( $domain, $this->domains_with_translations, true ) &&
-					str_starts_with( str_replace( "$location/", '', $mo_path ), "$domain-" )
+					str_starts_with( str_replace( "$location/", '', $file_path ), "$domain-" )
 				) {
 					$this->domains_with_translations[] = $domain;
 				}
 
-				if ( $mo_path === $path ) {
+				if ( $file_path === $mo_path || $file_path === $php_path ) {
 					$found_location = rtrim( $location, '/' ) . '/';
 				}
 			}
diff --git a/wp-includes/l10n.php b/wp-includes/l10n.php
index 228c40757c..8191b88cee 100644
--- a/wp-includes/l10n.php
+++ b/wp-includes/l10n.php
@@ -789,10 +789,6 @@ function load_textdomain( $domain, $mofile, $locale = null ) {
 	 */
 	$mofile = apply_filters( 'load_textdomain_mofile', $mofile, $domain );
 
-	if ( ! is_readable( $mofile ) ) {
-		return false;
-	}
-
 	if ( ! $locale ) {
 		$locale = determine_locale();
 	}
@@ -817,14 +813,14 @@ function load_textdomain( $domain, $mofile, $locale = null ) {
 		$preferred_format = 'php';
 	}
 
-	$translation_files = array( $mofile );
+	$translation_files = array();
+
 	if ( 'mo' !== $preferred_format ) {
-		array_unshift(
-			$translation_files,
-			substr_replace( $mofile, ".l10n.$preferred_format", - strlen( '.mo' ) )
-		);
+		$translation_files[] = substr_replace( $mofile, ".l10n.$preferred_format", - strlen( '.mo' ) );
 	}
 
+	$translation_files[] = $mofile;
+
 	foreach ( $translation_files as $file ) {
 		/**
 		 * Filters the file path for loading translations for the given text domain.
@@ -857,7 +853,7 @@ function load_textdomain( $domain, $mofile, $locale = null ) {
 		}
 	}
 
-	return true;
+	return false;
 }
 
 /**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7436f1d88e..524d2f9deb 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.5-alpha-57515';
+$wp_version = '6.5-alpha-57516';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.