diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index b7c46c9666d..fb996f7596d 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -584,9 +584,17 @@ impl Document {
     // https://html.spec.whatwg.org/multipage/#current-document-readiness
     pub fn set_ready_state(&self, state: DocumentReadyState) {
         match state {
-            DocumentReadyState::Loading => update_with_current_time(&self.dom_loading),
+            DocumentReadyState::Loading => {
+                // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserconnected
+                self.trigger_mozbrowser_event(MozBrowserEvent::Connected);
+                update_with_current_time(&self.dom_loading);
+            },
+            DocumentReadyState::Complete => {
+                // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadend
+                self.trigger_mozbrowser_event(MozBrowserEvent::LoadEnd);
+                update_with_current_time(&self.dom_complete);
+            },
             DocumentReadyState::Interactive => update_with_current_time(&self.dom_interactive),
-            DocumentReadyState::Complete => update_with_current_time(&self.dom_complete),
         };
 
         self.ready_state.set(state);
@@ -2587,9 +2595,6 @@ impl DocumentProgressHandler {
 
         document.notify_constellation_load();
 
-        // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadend
-        document.trigger_mozbrowser_event(MozBrowserEvent::LoadEnd);
-
         window.reflow(ReflowGoal::ForDisplay,
                       ReflowQueryType::NoQuery,
                       ReflowReason::DocumentLoaded);
diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index b59199d4909..4cf2c3f467e 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -303,7 +303,7 @@ impl MozBrowserEventDetailBuilder for HTMLIFrameElement {
         match event {
             MozBrowserEvent::AsyncScroll | MozBrowserEvent::Close | MozBrowserEvent::ContextMenu |
             MozBrowserEvent::Error | MozBrowserEvent::LoadEnd | MozBrowserEvent::LoadStart |
-            MozBrowserEvent::OpenWindow | MozBrowserEvent::OpenSearch  |
+            MozBrowserEvent::Connected | MozBrowserEvent::OpenWindow | MozBrowserEvent::OpenSearch  |
             MozBrowserEvent::UsernameAndPasswordRequired => {
                 rval.set(NullValue());
             }
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index a6d33bfebac..f0e115664af 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -415,6 +415,8 @@ pub enum MozBrowserEvent {
     Error,
     /// Sent when the favicon of a browser `<iframe>` changes.
     IconChange(String, String, String),
+    /// Sent when the browser `<iframe>` has reached the server.
+    Connected,
     /// Sent when the browser `<iframe>` has finished loading all its assets.
     LoadEnd,
     /// Sent when the browser `<iframe>` starts to load a new page.
@@ -441,6 +443,7 @@ impl MozBrowserEvent {
         match *self {
             MozBrowserEvent::AsyncScroll => "mozbrowserasyncscroll",
             MozBrowserEvent::Close => "mozbrowserclose",
+            MozBrowserEvent::Connected => "mozbrowserconnected",
             MozBrowserEvent::ContextMenu => "mozbrowsercontextmenu",
             MozBrowserEvent::Error => "mozbrowsererror",
             MozBrowserEvent::IconChange(_, _, _) => "mozbrowsericonchange",
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index bd0173ced8c..b12f912b49e 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -5934,6 +5934,12 @@
             "url": "/_mozilla/mozilla/mozbrowser/iframe_reload_twice.html"
           }
         ],
+        "mozilla/mozbrowser/mozbrowser_loadevents.html": [
+          {
+            "path": "mozilla/mozbrowser/mozbrowser_loadevents.html",
+            "url": "/_mozilla/mozilla/mozbrowser/mozbrowser_loadevents.html"
+          }
+        ],
         "mozilla/mozbrowser/mozbrowsericonchange_event.html": [
           {
             "path": "mozilla/mozbrowser/mozbrowsericonchange_event.html",
diff --git a/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowser_loadevents.html b/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowser_loadevents.html
new file mode 100644
index 00000000000..8992e7e743a
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/mozbrowser/mozbrowser_loadevents.html
@@ -0,0 +1,47 @@
+<head>
+  <title>mozbrowserloadstart, mozbrowserconnected and mozbrowserloadend are dispatched</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+  <script>
+
+    async_test(function(t) {
+
+      var has_reloaded = false;
+      var expectedEvents = [
+        "mozbrowserloadstart",
+        "mozbrowserconnected",
+        "mozbrowserloadend",
+        "mozbrowserloadstart",
+        "mozbrowserconnected",
+        "mozbrowserloadend",
+      ];
+
+      var receivedEvents = [];
+
+      var iframe = document.createElement("iframe");
+      iframe.mozbrowser = "true";
+      iframe.src = "http://web-platform.test:8000";
+
+      for (var event_name of ["mozbrowserloadstart",
+                              "mozbrowserconnected",
+                              "mozbrowserloadend"]) {
+        iframe.addEventListener(event_name, t.step_func(e => {
+          receivedEvents.push(e.type);
+          if (receivedEvents.length == expectedEvents.length) {
+            assert_array_equals(receivedEvents, expectedEvents);
+            t.done();
+          } else {
+            if (e.type == "mozbrowserloadend") {
+              iframe.reload();
+            }
+          }
+        }));
+      }
+
+      document.body.appendChild(iframe);
+    });
+
+  </script>
+</body>