diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 154cd2829c..5497828236 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -5,6 +5,57 @@
  * @package WordPress
  */
 
+/*
+	These next two functions are in this file due to compat.php having `__autoload`
+	in it and the PHP linter auto failing on it.
+*/
+
+if ( ! function_exists( 'str_starts_with' ) ) {
+	/**
+	 * Polyfill for `str_starts_with()` function added in PHP 8.0.
+	 *
+	 * Performs a case-sensitive check indicating if
+	 * the haystack begins with needle.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @param string $haystack The string to search in.
+	 * @param string $needle   The substring to search for in the `$haystack`.
+	 * @return bool True if `$haystack` starts with `$needle`, otherwise false.
+	 */
+	function str_starts_with( $haystack, $needle ) {
+		if ( '' === $needle ) {
+			return true;
+		}
+
+		return 0 === strpos( $haystack, $needle );
+	}
+}
+
+if ( ! function_exists( 'str_ends_with' ) ) {
+	/**
+	 * Polyfill for `str_ends_with()` function added in PHP 8.0.
+	 *
+	 * Performs a case-sensitive check indicating if
+	 * the haystack ends with needle.
+	 *
+	 * @since 5.9.0
+	 *
+	 * @param string $haystack The string to search in.
+	 * @param string $needle   The substring to search for in the `$haystack`.
+	 * @return bool True if `$haystack` ends with `$needle`, otherwise false.
+	 */
+	function str_ends_with( $haystack, $needle ) {
+		if ( '' === $haystack ) {
+			return '' === $needle;
+		}
+
+		$len = strlen( $needle );
+
+		return substr( $haystack, -$len, $len ) === $needle;
+	}
+}
+
 require( ABSPATH . WPINC . '/option.php' );
 
 /**