diff --git a/dom/events/EventNameList.h b/dom/events/EventNameList.h
index a995eb1cb445..20c225506275 100644
--- a/dom/events/EventNameList.h
+++ b/dom/events/EventNameList.h
@@ -172,6 +172,10 @@ EVENT(click,
       eMouseClick,
       EventNameType_All,
       eMouseEventClass)
+EVENT(close,
+      eClose,
+      EventNameType_HTML,
+      eBasicEventClass)
 EVENT(contextmenu,
       eContextMenu,
       EventNameType_HTMLXUL,
@@ -1090,4 +1094,3 @@ NON_IDL_EVENT(complete,
 #undef DOCUMENT_ONLY_EVENT
 #undef NON_IDL_EVENT
 #endif /* MESSAGE_TO_EVENT */
-
diff --git a/dom/html/HTMLDialogElement.cpp b/dom/html/HTMLDialogElement.cpp
index 1f796f9a6c8f..1f65b602f211 100644
--- a/dom/html/HTMLDialogElement.cpp
+++ b/dom/html/HTMLDialogElement.cpp
@@ -30,6 +30,9 @@ HTMLDialogElement::Close(const mozilla::dom::Optional<nsAString>& aReturnValue)
   ErrorResult ignored;
   SetOpen(false, ignored);
   ignored.SuppressException();
+  RefPtr<AsyncEventDispatcher> eventDispatcher =
+    new AsyncEventDispatcher(this, NS_LITERAL_STRING("close"), false);
+  eventDispatcher->PostDOMEvent();
 }
 
 void
diff --git a/dom/html/HTMLDialogElement.h b/dom/html/HTMLDialogElement.h
index 7abaee81ca0b..2222cd2f7cda 100644
--- a/dom/html/HTMLDialogElement.h
+++ b/dom/html/HTMLDialogElement.h
@@ -7,6 +7,7 @@
 #ifndef HTMLDialogElement_h
 #define HTMLDialogElement_h
 
+#include "mozilla/AsyncEventDispatcher.h"
 #include "mozilla/Attributes.h"
 #include "nsGenericHTMLElement.h"
 #include "nsGkAtoms.h"
diff --git a/dom/webidl/EventHandler.webidl b/dom/webidl/EventHandler.webidl
index 3949f80d0aab..971680abdaf0 100644
--- a/dom/webidl/EventHandler.webidl
+++ b/dom/webidl/EventHandler.webidl
@@ -38,7 +38,7 @@ interface GlobalEventHandlers {
            attribute EventHandler oncanplaythrough;
            attribute EventHandler onchange;
            attribute EventHandler onclick;
-           //(Not implemented)attribute EventHandler onclose;
+           attribute EventHandler onclose;
            attribute EventHandler oncontextmenu;
            //(Not implemented)attribute EventHandler oncuechange;
            attribute EventHandler ondblclick;
diff --git a/widget/EventMessageList.h b/widget/EventMessageList.h
index d3bff56380fc..4dbcd281a7f0 100644
--- a/widget/EventMessageList.h
+++ b/widget/EventMessageList.h
@@ -442,6 +442,9 @@ NS_EVENT_MESSAGE(eSelectionChange)
 // Details element events.
 NS_EVENT_MESSAGE(eToggle)
 
+// Dialog element events.
+NS_EVENT_MESSAGE(eClose)
+
 #ifdef UNDEF_NS_EVENT_MESSAGE_FIRST_LAST
 #undef UNDEF_NS_EVENT_MESSAGE_FIRST_LAST
 #undef NS_EVENT_MESSAGE_FIRST_LAST