Index: src/wp-includes/class-wp-admin-bar.php
===================================================================
--- src/wp-includes/class-wp-admin-bar.php	(revision 50466)
+++ src/wp-includes/class-wp-admin-bar.php	(working copy)
@@ -551,6 +551,8 @@
 
 			if ( 'onclick' === $attribute ) {
 				echo " $attribute='" . esc_js( $node->meta[ $attribute ] ) . "'";
+			} elseif ( 'title' === $attribute ) {
+				echo " aria-label='" . esc_attr( $node->meta[ $attribute ] ) . "'";
 			} else {
 				echo " $attribute='" . esc_attr( $node->meta[ $attribute ] ) . "'";
 			}