diff --git wp-includes/class-wp-customize-setting.php wp-includes/class-wp-customize-setting.php
index 0207b70..1fc976d 100644
--- wp-includes/class-wp-customize-setting.php
+++ wp-includes/class-wp-customize-setting.php
@@ -171,7 +171,16 @@ class WP_Customize_Setting {
 	 * @return false|null False if cap check fails or value isn't set.
 	 */
 	public final function save() {
-		$value = $this->post_value();
+
+		/**
+		 * Filter a Customize setting value before the setting is saved.
+		 *
+		 * @since 4.2.0
+		 *
+		 * @param mixed                $value Value of the setting.
+		 * @param WP_Customize_Setting $this  WP_Customize_Setting instance.
+		 */
+		$value = apply_filters( 'customize_save_value', $this->post_value(), $this );
 
 		if ( ! $this->check_capabilities() || ! isset( $value ) )
 			return false;