diff --git a/wp-admin/admin-ajax.php b/wp-admin/admin-ajax.php
index df75c17140..e62212ceeb 100644
--- a/wp-admin/admin-ajax.php
+++ b/wp-admin/admin-ajax.php
@@ -988,8 +988,10 @@ case 'autosave' : // The name of this action is hardcoded in edit_post()
 			$id = $post->ID;
 	}
 
-	if ( $do_lock && empty( $_POST['auto_draft'] ) && $id && is_numeric( $id ) )
-		wp_set_post_lock( $id );
+	if ( $do_lock && empty( $_POST['auto_draft'] ) && $id && is_numeric( $id ) ) {
+		$lock_result = wp_set_post_lock( $id );
+		$supplemental['active-post-lock'] = implode( ':', $lock_result );
+	}
 
 	if ( $nonce_age == 2 ) {
 		$supplemental['replace-autosavenonce'] = wp_create_nonce('autosave');
@@ -1551,6 +1553,26 @@ case 'wp-fullscreen-save-post' :
 	echo json_encode( array( 'message' => $message, 'last_edited' => $last_edited ) );
 	die();
 	break;
+case 'wp-remove-post-lock' :
+	if ( empty( $_POST['post_ID'] ) || empty( $_POST['active_post_lock'] ) )
+		die( '0' );
+	$post_id = (int) $_POST['post_ID'];
+	if ( ! $post = get_post( $post_id ) )
+		die( '0' );
+
+	check_ajax_referer( 'update-' . $post->post_type . '_' . $post_id );
+
+	if ( ! current_user_can( 'edit_post', $post_id ) )
+		die( '-1' );
+
+	$active_lock = array_map( 'absint', explode( ':', $_POST['active_post_lock'] ) );
+	if ( $active_lock[1] != get_current_user_id() )
+		die( '0' );
+
+	$new_lock = ( time() - apply_filters( 'wp_check_post_lock_window', AUTOSAVE_INTERVAL * 2 ) + 5 ) . ':' . $active_lock[1];
+	update_post_meta( $post_id, '_edit_lock', $new_lock, implode( ':', $active_lock ) );
+	die( '1' );
+
 default :
 	do_action( 'wp_ajax_' . $_POST['action'] );
 	die('0');
diff --git a/wp-admin/edit-form-advanced.php b/wp-admin/edit-form-advanced.php
index 695db43cd3..5449626cf9 100644
--- a/wp-admin/edit-form-advanced.php
+++ b/wp-admin/edit-form-advanced.php
@@ -231,7 +231,10 @@ require_once('./admin-header.php');
 <input type="hidden" id="post_type" name="post_type" value="<?php echo esc_attr( $post_type ) ?>" />
 <input type="hidden" id="original_post_status" name="original_post_status" value="<?php echo esc_attr( $post->post_status) ?>" />
 <input type="hidden" id="referredby" name="referredby" value="<?php echo esc_url(stripslashes(wp_get_referer())); ?>" />
+<?php if ( ! empty( $active_post_lock ) ) { ?>
+<input type="hidden" id="active_post_lock" value="<?php echo esc_attr( implode( ':', $active_post_lock ) ); ?>" />
 <?php
+}
 if ( 'draft' != $post->post_status )
 	wp_original_referer_field(true, 'previous');
 
diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index b204ef1cb4..735716c01e 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -1239,7 +1239,8 @@ function wp_check_post_lock( $post_id ) {
  * @since 2.5.0
  *
  * @param int $post_id ID of the post to being edited
- * @return bool Returns false if the post doesn't exist of there is no current user
+ * @return bool|array Returns false if the post doesn't exist of there is no current user, or
+ * 	an array of the lock time and the user ID.
  */
 function wp_set_post_lock( $post_id ) {
 	if ( !$post = get_post( $post_id ) )
@@ -1251,6 +1252,7 @@ function wp_set_post_lock( $post_id ) {
 	$lock = "$now:$user_id";
 
 	update_post_meta( $post->ID, '_edit_lock', $lock );
+	return array( $now, $user_id );
 }
 
 /**
diff --git a/wp-admin/post.php b/wp-admin/post.php
index df9e5a528c..6e3fa49641 100644
--- a/wp-admin/post.php
+++ b/wp-admin/post.php
@@ -174,7 +174,7 @@ case 'edit':
 	if ( $last = wp_check_post_lock( $post->ID ) ) {
 		add_action('admin_notices', '_admin_notice_post_locked' );
 	} else {
-		wp_set_post_lock( $post->ID );
+		$active_post_lock = wp_set_post_lock( $post->ID );
 		wp_enqueue_script('autosave');
 	}
 
diff --git a/wp-includes/js/autosave.dev.js b/wp-includes/js/autosave.dev.js
index aa4181152e..e3f53cdf4d 100644
--- a/wp-includes/js/autosave.dev.js
+++ b/wp-includes/js/autosave.dev.js
@@ -1,4 +1,4 @@
-var autosave, autosaveLast = '', autosavePeriodical, autosaveOldMessage = '', autosaveDelayPreview = false, notSaved = true, blockSave = false, fullscreen;
+var autosave, autosaveLast = '', autosavePeriodical, autosaveOldMessage = '', autosaveDelayPreview = false, notSaved = true, blockSave = false, fullscreen, autosaveLockRelease = true;
 
 jQuery(document).ready( function($) {
 	var dotabkey = true;
@@ -9,6 +9,7 @@ jQuery(document).ready( function($) {
 	//Disable autosave after the form has been submitted
 	$("#post").submit(function() {
 		$.cancel(autosavePeriodical);
+		autosaveLockRelease = false;
 	});
 
 	$('input[type="submit"], a.submitdelete', '#submitpost').click(function(){
@@ -47,6 +48,22 @@ jQuery(document).ready( function($) {
 		}
 	};
 
+	$(window).unload( function() {
+		if ( ! autosaveLockRelease )
+			return;
+		$.ajax({
+			type: 'POST',
+			url: ajaxurl,
+			async: false,
+			data: {
+				action: 'wp-remove-post-lock',
+				_wpnonce: $('#_wpnonce').val(),
+				post_ID: $('#post_ID').val(),
+				active_post_lock: $('#active_post_lock').val()
+			},
+		});
+	} );
+
 	// preview
 	$('#post-preview').click(function(){
 		if ( $('#auto_draft').val() == '1' && notSaved ) {
@@ -99,9 +116,14 @@ function autosave_parse_response(response) {
 			sup = res.responses[0].supplemental;
 			if ( 'disable' == sup['disable_autosave'] ) {
 				autosave = function() {};
+				autosaveLockRelease = false;
 				res = { errors: true };
 			}
 
+			if ( sup['active-post-lock'] ) {
+				jQuery('#active_post_lock').val( sup['active-post-lock'] );
+			}
+
 			if ( sup['alert'] ) {
 				jQuery('#autosave-alert').remove();
 				jQuery('#titlediv').after('<div id="autosave-alert" class="error below-h2"><p>' + sup['alert'] + '</p></div>');
diff --git a/wp-includes/js/autosave.js b/wp-includes/js/autosave.js
index ee06aaf562..b5ff20b8d7 100644
--- a/wp-includes/js/autosave.js
+++ b/wp-includes/js/autosave.js
@@ -1 +1 @@
-var autosave,autosaveLast="",autosavePeriodical,autosaveOldMessage="",autosaveDelayPreview=false,notSaved=true,blockSave=false,fullscreen;jQuery(document).ready(function(b){var a=true;autosaveLast=b("#post #title").val()+b("#post #content").val();autosavePeriodical=b.schedule({time:autosaveL10n.autosaveInterval*1000,func:function(){autosave()},repeat:true,protect:true});b("#post").submit(function(){b.cancel(autosavePeriodical)});b('input[type="submit"], a.submitdelete',"#submitpost").click(function(){blockSave=true;window.onbeforeunload=null;b(":button, :submit","#submitpost").each(function(){var c=b(this);if(c.hasClass("button-primary")){c.addClass("button-primary-disabled")}else{c.addClass("button-disabled")}});if(b(this).attr("id")=="publish"){b("#ajax-loading").css("visibility","visible")}else{b("#draft-ajax-loading").css("visibility","visible")}});window.onbeforeunload=function(){var c=typeof(tinyMCE)!="undefined"?tinyMCE.activeEditor:false,e,d;if(c&&!c.isHidden()){if(c.isDirty()){return autosaveL10n.saveAlert}}else{if(fullscreen&&fullscreen.settings.visible){e=b("#wp-fullscreen-title").val();d=b("#wp_mce_fullscreen").val()}else{e=b("#post #title").val();d=b("#post #content").val()}if((e||d)&&e+d!=autosaveLast){return autosaveL10n.saveAlert}}};b("#post-preview").click(function(){if(b("#auto_draft").val()=="1"&&notSaved){autosaveDelayPreview=true;autosave();return false}doPreview();return false});doPreview=function(){b("input#wp-preview").val("dopreview");b("form#post").attr("target","wp-preview").submit().attr("target","");b("input#wp-preview").val("")};if(typeof tinyMCE!="undefined"){b("#title")[b.browser.opera?"keypress":"keydown"](function(c){if(c.which==9&&!c.shiftKey&&!c.controlKey&&!c.altKey){if((b("#auto_draft").val()=="1")&&(b("#title").val().length>0)){autosave()}if(tinyMCE.activeEditor&&!tinyMCE.activeEditor.isHidden()&&a){c.preventDefault();a=false;tinyMCE.activeEditor.focus();return false}}})}if("1"==b("#auto_draft").val()){b("#title").blur(function(){if(!this.value||b("#auto_draft").val()!="1"){return}delayed_autosave()})}});function autosave_parse_response(c){var d=wpAjax.parseAjaxResponse(c,"autosave"),e="",a,b;if(d&&d.responses&&d.responses.length){e=d.responses[0].data;if(d.responses[0].supplemental){b=d.responses[0].supplemental;if("disable"==b.disable_autosave){autosave=function(){};d={errors:true}}if(b.alert){jQuery("#autosave-alert").remove();jQuery("#titlediv").after('<div id="autosave-alert" class="error below-h2"><p>'+b.alert+"</p></div>")}jQuery.each(b,function(f,g){if(f.match(/^replace-/)){jQuery("#"+f.replace("replace-","")).val(g)}})}if(!d.errors){a=parseInt(d.responses[0].id,10);if(!isNaN(a)&&a>0){autosave_update_slug(a)}}}if(e){jQuery(".autosave-message").html(e)}else{if(autosaveOldMessage&&d){jQuery(".autosave-message").html(autosaveOldMessage)}}return d}function autosave_saved(a){blockSave=false;autosave_parse_response(a);autosave_enable_buttons()}function autosave_saved_new(b){blockSave=false;var c=autosave_parse_response(b),a;if(c&&c.responses.length&&!c.errors){a=parseInt(c.responses[0].id,10);if(!isNaN(a)&&a>0){notSaved=false;jQuery("#auto_draft").val("0")}autosave_enable_buttons();if(autosaveDelayPreview){autosaveDelayPreview=false;doPreview()}}else{autosave_enable_buttons()}}function autosave_update_slug(a){if("undefined"!=makeSlugeditClickable&&jQuery.isFunction(makeSlugeditClickable)&&!jQuery("#edit-slug-box > *").size()){jQuery.post(ajaxurl,{action:"sample-permalink",post_id:a,new_title:fullscreen&&fullscreen.settings.visible?jQuery("#wp-fullscreen-title").val():jQuery("#title").val(),samplepermalinknonce:jQuery("#samplepermalinknonce").val()},function(b){if(b!=="-1"){jQuery("#edit-slug-box").html(b);makeSlugeditClickable()}})}}function autosave_loading(){jQuery(".autosave-message").html(autosaveL10n.savingText)}function autosave_enable_buttons(){setTimeout(function(){jQuery(":button, :submit","#submitpost").removeAttr("disabled");jQuery(".ajax-loading").css("visibility","hidden")},500)}function autosave_disable_buttons(){jQuery(":button, :submit","#submitpost").prop("disabled",true);setTimeout(autosave_enable_buttons,5000)}function delayed_autosave(){setTimeout(function(){if(blockSave){return}autosave()},200)}autosave=function(){blockSave=true;var c=(typeof tinyMCE!="undefined")&&tinyMCE.activeEditor&&!tinyMCE.activeEditor.isHidden(),d,f,b,e,a;autosave_disable_buttons();d={action:"autosave",post_ID:jQuery("#post_ID").val()||0,autosavenonce:jQuery("#autosavenonce").val(),post_type:jQuery("#post_type").val()||"",autosave:1};jQuery(".tags-input").each(function(){d[this.name]=this.value});f=true;if(jQuery("#TB_window").css("display")=="block"){f=false}if(c&&f){b=tinyMCE.activeEditor;if(b.plugins.spellchecker&&b.plugins.spellchecker.active){f=false}else{if("mce_fullscreen"==b.id||"wp_mce_fullscreen"==b.id){tinyMCE.get("content").setContent(b.getContent({format:"raw"}),{format:"raw"})}tinyMCE.triggerSave()}}if(fullscreen&&fullscreen.settings.visible){d.post_title=jQuery("#wp-fullscreen-title").val();d.content=jQuery("#wp_mce_fullscreen").val()}else{d.post_title=jQuery("#title").val();d.content=jQuery("#content").val()}if(jQuery("#post_name").val()){d.post_name=jQuery("#post_name").val()}if((d.post_title.length==0&&d.content.length==0)||d.post_title+d.content==autosaveLast){f=false}e=jQuery("#original_post_status").val();goodcats=([]);jQuery("[name='post_category[]']:checked").each(function(g){goodcats.push(this.value)});d.catslist=goodcats.join(",");if(jQuery("#comment_status").prop("checked")){d.comment_status="open"}if(jQuery("#ping_status").prop("checked")){d.ping_status="open"}if(jQuery("#excerpt").size()){d.excerpt=jQuery("#excerpt").val()}if(jQuery("#post_author").size()){d.post_author=jQuery("#post_author").val()}if(jQuery("#parent_id").val()){d.parent_id=jQuery("#parent_id").val()}d.user_ID=jQuery("#user-id").val();if(jQuery("#auto_draft").val()=="1"){d.auto_draft="1"}if(f){autosaveLast=d.post_title+d.content;jQuery(document).triggerHandler("wpcountwords",[d.content])}else{d.autosave=0}if(d.auto_draft=="1"){a=autosave_saved_new}else{a=autosave_saved}autosaveOldMessage=jQuery("#autosave").html();jQuery.ajax({data:d,beforeSend:f?autosave_loading:null,type:"POST",url:ajaxurl,success:a})};
\ No newline at end of file
+var autosave,autosaveLast="",autosavePeriodical,autosaveOldMessage="",autosaveDelayPreview=false,notSaved=true,blockSave=false,fullscreen,autosaveLockRelease=true;jQuery(document).ready(function(b){var a=true;autosaveLast=b("#post #title").val()+b("#post #content").val();autosavePeriodical=b.schedule({time:autosaveL10n.autosaveInterval*1000,func:function(){autosave()},repeat:true,protect:true});b("#post").submit(function(){b.cancel(autosavePeriodical);autosaveLockRelease=false});b('input[type="submit"], a.submitdelete',"#submitpost").click(function(){blockSave=true;window.onbeforeunload=null;b(":button, :submit","#submitpost").each(function(){var c=b(this);if(c.hasClass("button-primary")){c.addClass("button-primary-disabled")}else{c.addClass("button-disabled")}});if(b(this).attr("id")=="publish"){b("#ajax-loading").css("visibility","visible")}else{b("#draft-ajax-loading").css("visibility","visible")}});window.onbeforeunload=function(){var c=typeof(tinyMCE)!="undefined"?tinyMCE.activeEditor:false,e,d;if(c&&!c.isHidden()){if(c.isDirty()){return autosaveL10n.saveAlert}}else{if(fullscreen&&fullscreen.settings.visible){e=b("#wp-fullscreen-title").val();d=b("#wp_mce_fullscreen").val()}else{e=b("#post #title").val();d=b("#post #content").val()}if((e||d)&&e+d!=autosaveLast){return autosaveL10n.saveAlert}}};b(window).unload(function(){if(!autosaveLockRelease){return}b.ajax({type:"POST",url:ajaxurl,async:false,data:{action:"wp-remove-post-lock",_wpnonce:b("#_wpnonce").val(),post_ID:b("#post_ID").val(),active_post_lock:b("#active_post_lock").val()},})});b("#post-preview").click(function(){if(b("#auto_draft").val()=="1"&&notSaved){autosaveDelayPreview=true;autosave();return false}doPreview();return false});doPreview=function(){b("input#wp-preview").val("dopreview");b("form#post").attr("target","wp-preview").submit().attr("target","");b("input#wp-preview").val("")};if(typeof tinyMCE!="undefined"){b("#title")[b.browser.opera?"keypress":"keydown"](function(c){if(c.which==9&&!c.shiftKey&&!c.controlKey&&!c.altKey){if((b("#auto_draft").val()=="1")&&(b("#title").val().length>0)){autosave()}if(tinyMCE.activeEditor&&!tinyMCE.activeEditor.isHidden()&&a){c.preventDefault();a=false;tinyMCE.activeEditor.focus();return false}}})}if("1"==b("#auto_draft").val()){b("#title").blur(function(){if(!this.value||b("#auto_draft").val()!="1"){return}delayed_autosave()})}});function autosave_parse_response(c){var d=wpAjax.parseAjaxResponse(c,"autosave"),e="",a,b;if(d&&d.responses&&d.responses.length){e=d.responses[0].data;if(d.responses[0].supplemental){b=d.responses[0].supplemental;if("disable"==b.disable_autosave){autosave=function(){};autosaveLockRelease=false;d={errors:true}}if(b["active-post-lock"]){jQuery("#active_post_lock").val(b["active-post-lock"])}if(b.alert){jQuery("#autosave-alert").remove();jQuery("#titlediv").after('<div id="autosave-alert" class="error below-h2"><p>'+b.alert+"</p></div>")}jQuery.each(b,function(f,g){if(f.match(/^replace-/)){jQuery("#"+f.replace("replace-","")).val(g)}})}if(!d.errors){a=parseInt(d.responses[0].id,10);if(!isNaN(a)&&a>0){autosave_update_slug(a)}}}if(e){jQuery(".autosave-message").html(e)}else{if(autosaveOldMessage&&d){jQuery(".autosave-message").html(autosaveOldMessage)}}return d}function autosave_saved(a){blockSave=false;autosave_parse_response(a);autosave_enable_buttons()}function autosave_saved_new(b){blockSave=false;var c=autosave_parse_response(b),a;if(c&&c.responses.length&&!c.errors){a=parseInt(c.responses[0].id,10);if(!isNaN(a)&&a>0){notSaved=false;jQuery("#auto_draft").val("0")}autosave_enable_buttons();if(autosaveDelayPreview){autosaveDelayPreview=false;doPreview()}}else{autosave_enable_buttons()}}function autosave_update_slug(a){if("undefined"!=makeSlugeditClickable&&jQuery.isFunction(makeSlugeditClickable)&&!jQuery("#edit-slug-box > *").size()){jQuery.post(ajaxurl,{action:"sample-permalink",post_id:a,new_title:fullscreen&&fullscreen.settings.visible?jQuery("#wp-fullscreen-title").val():jQuery("#title").val(),samplepermalinknonce:jQuery("#samplepermalinknonce").val()},function(b){if(b!=="-1"){jQuery("#edit-slug-box").html(b);makeSlugeditClickable()}})}}function autosave_loading(){jQuery(".autosave-message").html(autosaveL10n.savingText)}function autosave_enable_buttons(){setTimeout(function(){jQuery(":button, :submit","#submitpost").removeAttr("disabled");jQuery(".ajax-loading").css("visibility","hidden")},500)}function autosave_disable_buttons(){jQuery(":button, :submit","#submitpost").prop("disabled",true);setTimeout(autosave_enable_buttons,5000)}function delayed_autosave(){setTimeout(function(){if(blockSave){return}autosave()},200)}autosave=function(){blockSave=true;var c=(typeof tinyMCE!="undefined")&&tinyMCE.activeEditor&&!tinyMCE.activeEditor.isHidden(),d,f,b,e,a;autosave_disable_buttons();d={action:"autosave",post_ID:jQuery("#post_ID").val()||0,autosavenonce:jQuery("#autosavenonce").val(),post_type:jQuery("#post_type").val()||"",autosave:1};jQuery(".tags-input").each(function(){d[this.name]=this.value});f=true;if(jQuery("#TB_window").css("display")=="block"){f=false}if(c&&f){b=tinyMCE.activeEditor;if(b.plugins.spellchecker&&b.plugins.spellchecker.active){f=false}else{if("mce_fullscreen"==b.id||"wp_mce_fullscreen"==b.id){tinyMCE.get("content").setContent(b.getContent({format:"raw"}),{format:"raw"})}tinyMCE.triggerSave()}}if(fullscreen&&fullscreen.settings.visible){d.post_title=jQuery("#wp-fullscreen-title").val();d.content=jQuery("#wp_mce_fullscreen").val()}else{d.post_title=jQuery("#title").val();d.content=jQuery("#content").val()}if(jQuery("#post_name").val()){d.post_name=jQuery("#post_name").val()}if((d.post_title.length==0&&d.content.length==0)||d.post_title+d.content==autosaveLast){f=false}e=jQuery("#original_post_status").val();goodcats=([]);jQuery("[name='post_category[]']:checked").each(function(g){goodcats.push(this.value)});d.catslist=goodcats.join(",");if(jQuery("#comment_status").prop("checked")){d.comment_status="open"}if(jQuery("#ping_status").prop("checked")){d.ping_status="open"}if(jQuery("#excerpt").size()){d.excerpt=jQuery("#excerpt").val()}if(jQuery("#post_author").size()){d.post_author=jQuery("#post_author").val()}if(jQuery("#parent_id").val()){d.parent_id=jQuery("#parent_id").val()}d.user_ID=jQuery("#user-id").val();if(jQuery("#auto_draft").val()=="1"){d.auto_draft="1"}if(f){autosaveLast=d.post_title+d.content;jQuery(document).triggerHandler("wpcountwords",[d.content])}else{d.autosave=0}if(d.auto_draft=="1"){a=autosave_saved_new}else{a=autosave_saved}autosaveOldMessage=jQuery("#autosave").html();jQuery.ajax({data:d,beforeSend:f?autosave_loading:null,type:"POST",url:ajaxurl,success:a})};
\ No newline at end of file
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index 41a93ba3ff..c3047b4afe 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -101,7 +101,7 @@ function wp_default_scripts( &$scripts ) {
 		'close' => __('Close'),
 	) );
 
-	$scripts->add( 'autosave', "/wp-includes/js/autosave$suffix.js", array('schedule', 'wp-ajax-response'), '20110524', 1 );
+	$scripts->add( 'autosave', "/wp-includes/js/autosave$suffix.js", array('schedule', 'wp-ajax-response'), '20110927', 1 );
 
 	$scripts->add( 'wp-lists', "/wp-includes/js/wp-lists$suffix.js", array('wp-ajax-response'), '20110521', 1 );