diff --git wp-includes/default-constants.php wp-includes/default-constants.php
index ae97efd..b22e24c 100644
--- wp-includes/default-constants.php
+++ wp-includes/default-constants.php
@@ -71,6 +71,11 @@ function wp_initial_constants() {
 	if ( !defined('WP_CACHE') )
 		define('WP_CACHE', false);
 
+	// Persistent database connections
+	if( !defined( 'DB_PERSISTENT' ) ) {
+		define( 'DB_PERSISTENT', false );
+	}
+
 	/**
 	 * Private
 	 */
diff --git wp-includes/wp-db.php wp-includes/wp-db.php
index 5178317..ddf4304 100644
--- wp-includes/wp-db.php
+++ wp-includes/wp-db.php
@@ -1417,6 +1417,10 @@ class wpdb {
 				}
 			}
 
+			if( DB_PERSISTENT ) {
+				$host = "p:$host";
+			}
+			
 			if ( WP_DEBUG ) {
 				mysqli_real_connect( $this->dbh, $host, $this->dbuser, $this->dbpassword, null, $port, $socket, $client_flags );
 			} else {