diff --git a/testing/mochitest/Makefile.in b/testing/mochitest/Makefile.in
index 7bb3ba48312c..86b73957d85d 100644
--- a/testing/mochitest/Makefile.in
+++ b/testing/mochitest/Makefile.in
@@ -100,6 +100,7 @@ _SERV_FILES = 	\
 		$(topsrcdir)/netwerk/test/httpserver/httpd.js \
 		mozprefs.js \
 		pywebsocket_wrapper.py \
+ 	 	plain-loop.html \
 		$(NULL)	
 
 _PYWEBSOCKET_FILES = \
diff --git a/testing/mochitest/browser-test.js b/testing/mochitest/browser-test.js
index 6ccc5d0b99ff..d305825eef17 100644
--- a/testing/mochitest/browser-test.js
+++ b/testing/mochitest/browser-test.js
@@ -58,6 +58,7 @@ Tester.prototype = {
   EventUtils: {},
   SimpleTest: {},
 
+  loops: 0,
   checker: null,
   currentTestIndex: -1,
   lastStartTime: null,
@@ -69,6 +70,10 @@ Tester.prototype = {
   },
 
   start: function Tester_start() {
+    //if testOnLoad was not called, then gConfig is not defined
+    if(!gConfig)
+      gConfig = readConfig();
+    this.loops = gConfig.loops;
     this.dumper.dump("*** Start BrowserChrome Test Results ***\n");
     this._cs.registerListener(this);
 
@@ -124,33 +129,40 @@ Tester.prototype = {
   },
 
   finish: function Tester_finish(aSkipSummary) {
-    this._cs.unregisterListener(this);
-
-    this.dumper.dump("\nINFO TEST-START | Shutdown\n");
-    if (this.tests.length) {
-      this.dumper.dump("Browser Chrome Test Summary\n");
-
-      function sum(a,b) a+b;
-      var passCount = this.tests.map(function (f) f.passCount).reduce(sum);
-      var failCount = this.tests.map(function (f) f.failCount).reduce(sum);
-      var todoCount = this.tests.map(function (f) f.todoCount).reduce(sum);
-
-      this.dumper.dump("\tPassed: " + passCount + "\n" +
-                       "\tFailed: " + failCount + "\n" +
-                       "\tTodo: " + todoCount + "\n");
-    } else {
-      this.dumper.dump("TEST-UNEXPECTED-FAIL | (browser-test.js) | " +
-                       "No tests to run. Did you pass an invalid --test-path?");
+    if(this.loops > 0){
+      --this.loops;
+      this.currentTestIndex = -1;
+      this.nextTest();
+    }
+    else{
+      this._cs.unregisterListener(this);
+  
+      this.dumper.dump("\nINFO TEST-START | Shutdown\n");
+      if (this.tests.length) {
+        this.dumper.dump("Browser Chrome Test Summary\n");
+  
+        function sum(a,b) a+b;
+        var passCount = this.tests.map(function (f) f.passCount).reduce(sum);
+        var failCount = this.tests.map(function (f) f.failCount).reduce(sum);
+        var todoCount = this.tests.map(function (f) f.todoCount).reduce(sum);
+  
+        this.dumper.dump("\tPassed: " + passCount + "\n" +
+                         "\tFailed: " + failCount + "\n" +
+                         "\tTodo: " + todoCount + "\n");
+      } else {
+        this.dumper.dump("TEST-UNEXPECTED-FAIL | (browser-test.js) | " +
+                         "No tests to run. Did you pass an invalid --test-path?");
+      }
+  
+      this.dumper.dump("\n*** End BrowserChrome Test Results ***\n");
+  
+      this.dumper.done();
+  
+      // Tests complete, notify the callback and return
+      this.callback(this.tests);
+      this.callback = null;
+      this.tests = null;
     }
-
-    this.dumper.dump("\n*** End BrowserChrome Test Results ***\n");
-
-    this.dumper.done();
-
-    // Tests complete, notify the callback and return
-    this.callback(this.tests);
-    this.callback = null;
-    this.tests = null;
   },
 
   observe: function Tester_observe(aConsoleMessage) {
diff --git a/testing/mochitest/harness-overlay.xul b/testing/mochitest/harness-overlay.xul
index 7683fda13825..5df9c4af0686 100644
--- a/testing/mochitest/harness-overlay.xul
+++ b/testing/mochitest/harness-overlay.xul
@@ -32,7 +32,7 @@ function loadTests()
 {
   window.removeEventListener("load", loadTests, false);
   [links, singleTestPath] = getTestList();
-
+ 
   // load server.js in so we can share template functions
   var scriptLoader = Cc["@mozilla.org/moz/jssubscript-loader;1"].
                        getService(Ci.mozIJSSubScriptLoader);
@@ -49,10 +49,13 @@ function loadTests()
   }
   gTestList = eval(srvScope.jsonArrayOfTestFiles(links));
   populate();
-  hookup();
 
-  if (singleTestPath)
-    window.location.href = singleTestPath;
+  if (singleTestPath) {
+    TestRunner.loopTest(singleTestPath);
+  } else {
+    hookup();
+  }
+
 }
 
     window.addEventListener("load", loadTests, false);
@@ -63,6 +66,7 @@ function loadTests()
     <button label="Run Chrome Tests" id="runtests" flex="1"/>
 
     <body xmlns="http://www.w3.org/1999/xhtml" id="xulharness">
+      <!--TODO: this should be separated into a file that both this file and server.js uses-->
       <div class="container">
         <p style="float:right;">
           <small>Based on the MochiKit unit tests.</small>
@@ -98,6 +102,12 @@ function loadTests()
               </tr>
             </tbody>
           </table>
+          <br/>
+          <table cellpadding="0" cellspacing="0" border="1" bordercolor="red">
+          <!-- tbody needed to avoid bug 494546 causing performance problems -->
+            <tbody id="fail-table">
+            </tbody>
+          </table>
         </div>
       </div>
     </body>
diff --git a/testing/mochitest/plain-loop.html b/testing/mochitest/plain-loop.html
new file mode 100644
index 000000000000..1e97eae52261
--- /dev/null
+++ b/testing/mochitest/plain-loop.html
@@ -0,0 +1,80 @@
+<html>
+<head>
+  <link rel="stylesheet" type="text/css" href="/static/harness.css" />
+  <script type="text/javascript" src="/MochiKit/packed.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/TestRunner.js"></script>        
+  <script type="text/javascript" src="/tests/SimpleTest/MozillaFileLogger.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/setup.js"></script>
+  </head>
+  <script type="text/javascript">
+
+function loadTests()
+{
+  var links = {};
+  var params = {};
+  if (window.parseQueryString) {
+    params = parseQueryString(location.search.substring(1), true);
+  }
+
+  var table = $("test-table");
+  var row = table.rows[1];
+  row.id = 'tr-' + params.testname;
+  row.cells[3].innerHTML= "<a href=" + params.testname + ">" + params.testname + "</a>";
+
+  TestRunner.loopTest(params.testname);
+}
+</script>
+
+<body onload="loadTests()">
+      <!--TODO: this should be separated into a file that both this file and server.js uses-->
+      <div class="container">
+        <p style="float:right;">
+          <small>Based on the MochiKit unit tests.</small>
+        </p>
+        <div class="status">
+          <h1 id="indicator">Status</h1>
+          <h2 id="pass">Passed: <span id="pass-count">0</span></h2>
+          <h2 id="fail">Failed: <span id="fail-count">0</span></h2>
+          <h2 id="fail">Todo: <span id="todo-count">0</span></h2>
+        </div>
+        <div class="clear"></div>
+        <div id="current-test">
+          <b>Currently Executing: <span id="current-test-path">_</span></b>
+        </div>
+        <div class="clear"></div>
+        <div class="frameholder">
+          <iframe type="content" scrolling="no" id="testframe" width="550" height="350"></iframe>
+        </div>
+        <div class="clear"></div>
+        <div class="toggle">
+          <a href="#" id="toggleNonTests">Show Non-Tests</a>
+          <br />
+        </div>
+        <div id="wrapper">
+          <table cellpadding="0" cellspacing="0">
+          <!-- tbody needed to avoid bug 494546 causing performance problems -->
+            <tbody id="test-table">
+              <tr>
+                <td>Passed</td>
+                <td>Failed</td>
+                <td>Todo</td>
+                <td>Test Files</td>
+              </tr>
+              <tr class="dir">
+                <td>0</td>
+                <td>0</td>
+                <td>0</td>
+                <td></td>
+              </tr>
+            </tbody>
+          </table>
+          <br/>
+          <table cellpadding="0" cellspacing="0" border="1" bordercolor="red">
+          <!-- tbody needed to avoid bug 494546 causing performance problems -->
+            <tbody id="fail-table">
+            </tbody>
+          </table>
+        </div>
+      </div>
+</body>
+</html>
diff --git a/testing/mochitest/runtests.py b/testing/mochitest/runtests.py
index c5ac057fddfc..4364c4be1237 100644
--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -232,6 +232,13 @@ class MochitestOptions(optparse.OptionParser):
                            "inside a VMware Workstation 7.0 or later VM")
     defaults["vmwareRecording"] = False
 
+    self.add_option("--loops",
+                    action = "store", type = "int",
+                    dest = "loops", metavar = "LOOPS",
+                    help = "repeats the test or set of tests the given number of times "
+                           "without restarting the browser (given number > 0)")
+    defaults["loops"] = 0
+
     # -h, --help are automatically handled by OptionParser
 
     self.set_defaults(**defaults)
@@ -405,6 +412,7 @@ class Mochitest(object):
   # Path to the test script on the server
   TEST_PATH = "/tests/"
   CHROME_PATH = "/redirect.html";
+  PLAIN_LOOP_PATH = "/plain-loop.html";
   urlOpts = []
   runSSLTunnel = True
   vmwareHelper = None
@@ -433,6 +441,8 @@ class Mochitest(object):
     """ Build the url path to the specific test harness and test file or directory """
     testHost = "http://mochi.test:8888"
     testURL = testHost + self.TEST_PATH + options.testPath
+    if os.path.isfile(self.oldcwd + self.TEST_PATH + options.testPath) and options.loops > 0:
+       testURL = testHost + self.PLAIN_LOOP_PATH
     if options.chrome or options.a11y:
        testURL = testHost + self.CHROME_PATH
     elif options.browserChrome:
@@ -537,6 +547,7 @@ class Mochitest(object):
         totalChunks -- how many chunks to split tests into
         thisChunk -- which chunk to run
         timeout -- per-test timeout in seconds
+        loops -- How many times to run the test
     """
   
     # allow relative paths for logFile
@@ -563,6 +574,10 @@ class Mochitest(object):
         self.urlOpts.append("chunkByDir=%d" % options.chunkByDir)
       if options.shuffle:
         self.urlOpts.append("shuffle=1")
+      if options.loops:
+        self.urlOpts.append("loops=%d" % options.loops)
+      if os.path.isfile(self.oldcwd + self.TEST_PATH + options.testPath) and options.loops > 0:
+        self.urlOpts.append("testname=%s" % (self.TEST_PATH + options.testPath))
 
   def cleanup(self, manifest, options):
     """ remove temporary files and profile """
diff --git a/testing/mochitest/server.js b/testing/mochitest/server.js
index a21e2cb87a93..1131befd9e6b 100644
--- a/testing/mochitest/server.js
+++ b/testing/mochitest/server.js
@@ -662,6 +662,11 @@ function testListing(metadata, response)
             TR(TD("Passed"), TD("Failed"), TD("Todo"), TD("Test Files")),
             linksToTableRows(links, 0)
           ),
+
+          BR(),
+          TABLE({cellpadding: 0, cellspacing: 0, border: 1, bordercolor: "red", id: "fail-table"}
+          ),
+
           DIV({class: "clear"})
         )
       )
diff --git a/testing/mochitest/tests/SimpleTest/TestRunner.js b/testing/mochitest/tests/SimpleTest/TestRunner.js
index c15d0f88f243..8b6228181bc1 100644
--- a/testing/mochitest/tests/SimpleTest/TestRunner.js
+++ b/testing/mochitest/tests/SimpleTest/TestRunner.js
@@ -37,6 +37,7 @@ var TestRunner = {};
 TestRunner.logEnabled = false;
 TestRunner._currentTest = 0;
 TestRunner.currentTestURL = "";
+TestRunner.originalTestURL = "";
 TestRunner._urls = [];
 
 TestRunner.timeout = 5 * 60 * 1000; // 5 minutes.
@@ -85,6 +86,12 @@ TestRunner.requestLongerTimeout = function(factor) {
     TestRunner._timeoutFactor = factor;
 }
 
+/**
+ * This is used to loop tests
+**/
+TestRunner.loops = 0;
+TestRunner._currentLoop = 0;
+
 /**
  * This function is called after generating the summary.
 **/
@@ -124,7 +131,6 @@ TestRunner._toggle = function(el) {
     }
 };
 
-
 /**
  * Creates the iframe that contains a test
 **/
@@ -163,6 +169,7 @@ TestRunner._makeIframe = function (url, retry) {
 **/
 TestRunner.runTests = function (/*url...*/) {
     TestRunner.log("SimpleTest START");
+    TestRunner.originalTestURL = $("current-test").innerHTML;
 
     SpecialPowers.registerProcessCrashObservers();
 
@@ -174,6 +181,49 @@ TestRunner.runTests = function (/*url...*/) {
     TestRunner.runNextTest();
 };
 
+/**
+ * Used for running a set of tests in a loop for debugging purposes
+ * Takes an array of URLs
+**/
+TestRunner.resetTests = function(listURLs) {
+  TestRunner._currentTest = 0;
+  // Reset our "Current-test" line - functionality depends on it
+  $("current-test").innerHTML = TestRunner.originalTestURL;
+  if (TestRunner.logEnabled)
+    TestRunner.log("SimpleTest START Loop " + TestRunner._currentLoop);
+
+  TestRunner._urls = listURLs;
+  $('testframe').src="";
+  TestRunner._checkForHangs();
+  window.focus();
+  $('testframe').focus();
+  TestRunner.runNextTest();
+}
+
+/*
+ * Used to run a single test in a loop and update the UI with the results
+ */
+TestRunner.loopTest = function(testPath){
+ var numLoops = TestRunner.loops;
+  while(numLoops >= 0){
+    //must set the following line so that TestHarness.updateUI finds the right div to update
+    $("current-test-path").innerHTML = testPath;
+    function checkComplete() {
+      var testWindow = window.open(testPath, 'test window');
+      if (testWindow.document.readyState == "complete") {
+        TestRunner.currentTestURL = testPath;
+        TestRunner.updateUI(testWindow.SimpleTest._tests);
+        testWindow.close();
+      } else {
+        setTimeout(checkComplete, 1000);
+      }
+    }
+    checkComplete();
+    numLoops--;
+  }
+}
+
+/**
 /**
  * Run the next test. If no test remains, calls onComplete().
  **/
@@ -216,11 +266,27 @@ TestRunner.runNextTest = function() {
         TestRunner.log("Passed: " + $("pass-count").innerHTML);
         TestRunner.log("Failed: " + $("fail-count").innerHTML);
         TestRunner.log("Todo:   " + $("todo-count").innerHTML);
-        TestRunner.log("SimpleTest FINISHED");
+        // If we are looping, don't send this cause it closes the log file
+        if (TestRunner.loops == 0)
+          TestRunner.log("SimpleTest FINISHED");
 
-        if (TestRunner.onComplete) {
+        if (TestRunner.loops == 0 && TestRunner.onComplete) {
+             TestRunner.onComplete();
+         }
+ 
+        if (TestRunner._currentLoop < TestRunner.loops){
+          TestRunner._currentLoop++;
+          TestRunner.resetTests(TestRunner._urls);
+        } else {
+          // Loops are finished
+          if (TestRunner.logEnabled) {
+            TestRunner.log("TEST-INFO | Ran " + TestRunner._currentLoop + " Loops");
+            TestRunner.log("SimpleTest FINISHED");
+          }
+
+          if (TestRunner.onComplete)
             TestRunner.onComplete();
-        }
+       }
     }
 };
 
@@ -292,6 +358,47 @@ TestRunner.countResults = function(tests) {
   return {"OK": nOK, "notOK": nNotOK, "todo": nTodo};
 }
 
+/**
+ * Print out table of any error messages found during looped run
+ */
+TestRunner.displayLoopErrors = function(tableName, tests) {
+  if(TestRunner.countResults(tests).notOK >0){
+    var table = $(tableName);
+    var curtest;
+    if (table.rows.length == 0) {
+      //if table headers are not yet generated, make them
+      var row = table.insertRow(table.rows.length); 
+      var cell = row.insertCell(0);
+      var textNode = document.createTextNode("Test File Name:");
+      cell.appendChild(textNode);
+      cell = row.insertCell(1);
+      textNode = document.createTextNode("Test:");
+      cell.appendChild(textNode);
+      cell = row.insertCell(2);
+      textNode = document.createTextNode("Error message:");
+      cell.appendChild(textNode);
+    }
+  
+    //find the broken test
+    for (var testnum in tests){
+      curtest = tests[testnum];
+      if( !((curtest.todo && !curtest.result) || (curtest.result && !curtest.todo)) ){
+        //this is a failed test or the result of todo test. Display the related message
+        row = table.insertRow(table.rows.length); 
+        cell = row.insertCell(0);
+        textNode = document.createTextNode(TestRunner.currentTestURL);
+        cell.appendChild(textNode);
+        cell = row.insertCell(1);
+        textNode = document.createTextNode(curtest.name);
+        cell.appendChild(textNode);
+        cell = row.insertCell(2);
+        textNode = document.createTextNode((curtest.diag ? curtest.diag : "" ));
+        cell.appendChild(textNode);
+      }
+    }
+  }
+}
+
 TestRunner.updateUI = function(tests) {
   var results = TestRunner.countResults(tests);
   var passCount = parseInt($("pass-count").innerHTML) + results.OK;
@@ -319,9 +426,14 @@ TestRunner.updateUI = function(tests) {
   var row = $(trID);
   var tds = row.getElementsByTagName("td");
   tds[0].style.backgroundColor = "#0d0";
-  tds[0].innerHTML = results.OK;
+  tds[0].innerHTML = parseInt(tds[0].innerHTML) + parseInt(results.OK);
   tds[1].style.backgroundColor = results.notOK > 0 ? "red" : "#0d0";
-  tds[1].innerHTML = results.notOK;
+  tds[1].innerHTML = parseInt(tds[1].innerHTML) + parseInt(results.notOK);
   tds[2].style.backgroundColor = results.todo > 0 ? "orange" : "#0d0";
-  tds[2].innerHTML = results.todo;
+  tds[2].innerHTML = parseInt(tds[2].innerHTML) + parseInt(results.todo);
+
+  //if we ran in a loop, display any found errors
+  if(TestRunner.loops > 0){
+    TestRunner.displayLoopErrors('fail-table', tests);
+  }
 }
diff --git a/testing/mochitest/tests/SimpleTest/setup.js b/testing/mochitest/tests/SimpleTest/setup.js
index 9fa7dc855c84..9e27ef7dfb4f 100644
--- a/testing/mochitest/tests/SimpleTest/setup.js
+++ b/testing/mochitest/tests/SimpleTest/setup.js
@@ -69,6 +69,11 @@ if (params.timeout) {
 var fileLevel =  params.fileLevel || null;
 var consoleLevel = params.consoleLevel || null;
 
+// loop tells us how many times to run the tests
+if (params.loops) {
+  TestRunner.loops = params.loops;
+} 
+
 // closeWhenDone tells us to call quit.js when complete
 if (params.closeWhenDone) {
   TestRunner.onComplete = goQuitApplication;
@@ -154,6 +159,7 @@ RunSet.runall = function(e) {
   }
   TestRunner.runTests(my_tests);
 }
+
 RunSet.reloadAndRunAll = function(e) {
   e.preventDefault();
   //window.location.hash = "";
@@ -165,8 +171,7 @@ RunSet.reloadAndRunAll = function(e) {
     window.location.href += "&autorun=1";
   } else {
     window.location.href += "?autorun=1";
-  }
-  
+  }  
 };
 
 // UI Stuff
@@ -205,7 +210,7 @@ function toggleNonTests (e) {
 function hookup() {
   connect("runtests", "onclick", RunSet, "reloadAndRunAll");
   connect("toggleNonTests", "onclick", toggleNonTests);
-  // run automatically if
+  // run automatically if autorun specified
   if (params.autorun) {
     RunSet.runall();
   }