diff --git a/wp-admin/css/wp-admin.css b/wp-admin/css/wp-admin.css
index 49c0d7eaf2..7299d3f627 100644
--- a/wp-admin/css/wp-admin.css
+++ b/wp-admin/css/wp-admin.css
@@ -6785,6 +6785,23 @@ a.rsswidget {
 	width: auto;
 }
 
+.interim-login #login {
+	padding: 0;
+	width: 300px;
+}
+
+.interim-login.login h1 a {
+	width: auto;
+}
+
+.interim-login #login_error,
+.interim-login.login .message {
+	margin: 0 0 16px;
+}
+
+.interim-login.login form {
+	margin: 0;
+}
 
 /* ms */
 /* Dashboard: MS Specific Data */
diff --git a/wp-includes/class-wp-auth-check.php b/wp-includes/class-wp-auth-check.php
new file mode 100644
index 0000000000..b0338dc4bf
--- /dev/null
+++ b/wp-includes/class-wp-auth-check.php
@@ -0,0 +1,192 @@
+<?php
+/**
+ * Test the user's current authorization state
+ *
+ * @package WordPress
+ * @since 3.6.0
+ */
+class WP_Auth_Check {
+
+	/**
+	 * Holds the singleton instance of this object
+	 */
+	private static $_instance = null;
+
+	/**
+	 * Private constructor because we're a singleton
+	 */
+	private function __construct() {}
+
+	/**
+	 * Initialize the singleton
+	 */
+	public static function get_instance() {
+		$this_class = get_called_class(); // gets the right class when this is extended
+		if ( ! ( self::$_instance instanceof $this_class ) ) {
+			self::$_instance = new $this_class;
+			self::$_instance->_init();
+		}
+
+		return self::$_instance;
+	}
+
+	/**
+	 * Object init, sets up hooks. Not done in the constructor so that the
+	 * _init() method may be extended without breaking the singleton.
+	 */
+	protected function _init() {
+		if ( is_admin() ) {
+			add_action( 'admin_footer', array( $this, 'enqueue_scripts' ) );
+			add_action( 'admin_print_footer_scripts', array( $this, 'footer_js' ) );
+		} elseif ( is_user_logged_in() ) {
+			add_action( 'wp_footer', array( $this, 'enqueue_scripts' ) );
+			add_action( 'wp_print_footer_scripts', array( $this, 'footer_js' ) );
+		}
+
+		add_filter( 'heartbeat_received', array( $this, 'login' ), 10, 2 );
+		add_filter( 'heartbeat_nopriv_received', array( $this, 'nopriv_login' ), 10, 2 );
+	}
+
+	/**
+	 * Checks if the user is still logged in
+	 */
+	public function login( $response, $data ) {
+		if ( array_key_exists('wp-auth-check', $data) && ( ! isset( $_COOKIE[LOGGED_IN_COOKIE] ) || ! wp_validate_auth_cookie() || ! empty( $GLOBALS['login_grace_period'] ) ) )
+			$response['wp-auth-check-html'] = $this->notice();
+
+		
+		$response['LOGGED_IN_COOKIE'] = isset( $_COOKIE[LOGGED_IN_COOKIE] );
+		
+		$response['wp_validate_auth_cookie'] = wp_validate_auth_cookie();
+		
+		return $response;
+	}
+
+	/**
+	 * Runs when a user is expected to be logged in
+	 * but has logged out or cannot be validated
+	 */
+	public function nopriv_login( $response, $data ) {
+		if ( array_key_exists('wp-auth-check', $data) )
+			$response['wp-auth-check-html'] = $this->notice();
+
+		
+		$response['nopriv_login'] = 1;
+		
+		
+		return $response;
+	}
+	
+	public function footer_js() {
+		?>
+		<script>
+		(function($){
+			$( document ).on( 'heartbeat-tick.wp-auth-check', function( e, data ) {
+				var wrap = $('#wp-auth-check-notice-wrap');
+
+				if ( data['wp-auth-check-html'] && ! wrap.length ) {
+					$('body').append( data['wp-auth-check-html'] );
+				} else if ( !data['wp-auth-check-html'] && wrap.length && ! wrap.data('logged-in') ) {
+					wrap.remove();
+				}
+			}).on( 'heartbeat-send.wp-auth-check', function( e, data ) {
+				data['wp-auth-check'] = 1;
+			});
+		}(jQuery));
+		</script>
+		<?php
+	}
+
+	public function enqueue_scripts() {
+		// This will also enqueue jQuery
+		wp_enqueue_script( 'heartbeat' );
+	}
+
+	/**
+	 * Returns the login notice
+	 */
+	public function notice() {
+		// Inline JS and CSS, keep the notice portable.
+		return '
+<div id="wp-auth-check-notice-wrap">
+<style type="text/css" scoped>
+#wp-auth-check {
+	position: fixed;
+	height: 90%;
+	left: 50%;
+	max-height: 415px;
+	overflow: auto;
+	top: 35px;
+	width: 300px;
+	margin: 0 0 0 -160px;
+	padding: 12px 20px;
+	border: 1px solid #ddd;
+	background-color: #fbfbfb;
+	-webkit-border-radius: 3px;
+	border-radius: 3px;
+	z-index: 1000000000;
+}
+#wp-auth-check-form {
+	background: url("' . admin_url('/images/wpspin_light-2x.gif') . '") no-repeat center center;
+	background-size: 16px 16px;
+}
+#wp-auth-check-form iframe {
+	height: 100%;
+	overflow: hidden;
+}
+#wp-auth-check a.wp-auth-check-close {
+	position: absolute;
+	right: 8px;
+	top: 8px;
+	width: 24px;
+	height: 24px;
+	background: url("' . includes_url('images/uploader-icons.png') . '") no-repeat scroll -95px center transparent;
+}
+#wp-auth-check h3 {
+	margin: 0 0 12px;
+	padding: 0;
+	font-size: 1.25em;
+}
+@media print,
+  (-o-min-device-pixel-ratio: 5/4),
+  (-webkit-min-device-pixel-ratio: 1.25),
+  (min-resolution: 120dpi) {
+	#wp-auth-check a.wp-auth-check-close {
+		background-image: url("' . includes_url('images/uploader-icons-2x.png') . '");
+		background-size: 134px 15px;
+	}
+}
+</style>
+<div id="wp-auth-check" tabindex="0">
+<h3>' .  __('Session expired') . '</h3>
+<a href="#" class="wp-auth-check-close"><span class="screen-reader-text">' . __('close') . '</span></a>
+<div id="wp-auth-check-form">
+	<iframe src="' . esc_url( add_query_arg( array( 'interim-login' => 1 ), wp_login_url() ) ) . '" frameborder="0"></iframe>
+</div>
+</div>
+<script type="text/javascript">
+(function($){
+var el, wrap = $("#wp-auth-check-notice-wrap");
+el = $("#wp-auth-check").focus().find("a.wp-auth-check-close").on("click", function(e){
+	el.fadeOut(200, function(){ wrap.remove(); });
+	e.preventDefault();
+});
+$("#wp-auth-check-form iframe").load(function(){
+	var height;
+	try { height = $(this.contentWindow.document).find("#login").height(); } catch(er){}
+	if ( height ) {
+		$("#wp-auth-check").css("max-height", height + 40 + "px");
+		$(this).css("height", height + 5 + "px");
+		if ( height < 200 ) {
+			wrap.data("logged-in", true);
+			setTimeout( function(){ wrap.fadeOut(200, function(){ wrap.remove(); }); }, 5000 );
+		}
+	}
+});
+}(jQuery));
+</script>
+</div>';
+
+	}
+}
+
diff --git a/wp-includes/default-filters.php b/wp-includes/default-filters.php
index d6d877ded0..cdc4e9cbdf 100644
--- a/wp-includes/default-filters.php
+++ b/wp-includes/default-filters.php
@@ -294,4 +294,7 @@ add_filter( 'default_option_embed_autourls', '__return_true' );
 // Default settings for heartbeat
 add_filter( 'heartbeat_settings', 'wp_heartbeat_settings' );
 
+// Check if the user is logged out
+add_action( 'admin_init', 'wp_auth_check_load' );
+
 unset($filter, $action);
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index cbd7925a77..829ca7104b 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -3883,4 +3883,18 @@ function wp_is_stream( $path ) {
  */
 function wp_checkdate( $month, $day, $year, $source_date ) {
 	return apply_filters( 'wp_checkdate', checkdate( $month, $day, $year ), $source_date );
-}
\ No newline at end of file
+}
+
+/**
+ * Load the auth check, for monitoring whether the user is still logged in
+ *
+ * @since 3.6.0
+ *
+ * @return void
+ */
+function wp_auth_check_load() {
+	if ( ! class_exists('WP_Auth_Check') ) {
+		require( ABSPATH . WPINC . '/class-wp-auth-check.php' );
+		WP_Auth_Check::get_instance();
+	}
+}
diff --git a/wp-login.php b/wp-login.php
index 92d3911815..e35e359e1d 100644
--- a/wp-login.php
+++ b/wp-login.php
@@ -51,7 +51,7 @@ function login_header($title = 'Log In', $message = '', $wp_error = '') {
 	$shake_error_codes = array( 'empty_password', 'empty_email', 'invalid_email', 'invalidcombo', 'empty_username', 'invalid_username', 'incorrect_password' );
 	$shake_error_codes = apply_filters( 'shake_error_codes', $shake_error_codes );
 
-	if ( $shake_error_codes && $wp_error->get_error_code() && in_array( $wp_error->get_error_code(), $shake_error_codes ) )
+	if ( ! $interim_login && $shake_error_codes && $wp_error->get_error_code() && in_array( $wp_error->get_error_code(), $shake_error_codes ) )
 		add_action( 'login_head', 'wp_shake_js', 12 );
 
 	?><!DOCTYPE html>
@@ -82,16 +82,19 @@ function login_header($title = 'Log In', $message = '', $wp_error = '') {
 	$login_header_url   = apply_filters( 'login_headerurl',   $login_header_url   );
 	$login_header_title = apply_filters( 'login_headertitle', $login_header_title );
 
-	// Don't allow interim logins to navigate away from the page.
-	if ( $interim_login )
-		$login_header_url = '#';
-
 	$classes = array( 'login-action-' . $action, 'wp-core-ui' );
 	if ( wp_is_mobile() )
 		$classes[] = 'mobile';
 	if ( is_rtl() )
 		$classes[] = 'rtl';
+	if ( $interim_login ) {
+		// Don't allow interim logins to navigate away from the page.
+		$login_header_url = '#';
+		$classes[] = 'interim-login';
+	}
+
 	$classes = apply_filters( 'login_body_class', $classes, $action );
+
 	?>
 	</head>
 	<body class="login <?php echo esc_attr( implode( ' ', $classes ) ); ?>">
@@ -613,12 +616,6 @@ default:
 		if ( $interim_login ) {
 			$message = '<p class="message">' . __('You have logged in successfully.') . '</p>';
 			login_header( '', $message ); ?>
-
-			<?php if ( ! $customize_login ) : ?>
-			<script type="text/javascript">setTimeout( function(){window.close()}, 8000);</script>
-			<p class="alignright">
-			<input type="button" class="button-primary" value="<?php esc_attr_e('Close'); ?>" onclick="window.close()" /></p>
-			<?php endif; ?>
 			</div>
 			<?php do_action( 'login_footer' ); ?>
 			<?php if ( $customize_login ) : ?>
@@ -662,7 +659,7 @@ default:
 	elseif	( isset($_GET['checkemail']) && 'registered' == $_GET['checkemail'] )
 		$errors->add('registered', __('Registration complete. Please check your e-mail.'), 'message');
 	elseif	( $interim_login )
-		$errors->add('expired', __('Your session has expired. Please log-in again.'), 'message');
+		$errors->add('expired', __('Please log-in again. You will not move away from this page.'), 'message');
 	elseif ( strpos( $redirect_to, 'about.php?updated' ) )
 		$errors->add('updated', __( '<strong>You have successfully updated WordPress!</strong> Please log back in to experience the awesomeness.' ), 'message' );