diff --git a/dom/indexedDB/IDBFactory.cpp b/dom/indexedDB/IDBFactory.cpp
index f1c3010423e..43b39176c50 100644
--- a/dom/indexedDB/IDBFactory.cpp
+++ b/dom/indexedDB/IDBFactory.cpp
@@ -61,7 +61,7 @@
 #include "IDBKeyRange.h"
 #include "LazyIdleThread.h"
 
-#define DB_SCHEMA_VERSION 2
+#define DB_SCHEMA_VERSION 3
 
 USING_INDEXEDDB_NAMESPACE
 
@@ -165,10 +165,9 @@ CreateTables(mozIStorageConnection* aDBConn)
   // Table `ai_object_data`
   rv = aDBConn->ExecuteSimpleSQL(NS_LITERAL_CSTRING(
     "CREATE TABLE ai_object_data ("
-      "id INTEGER, "
+      "id INTEGER PRIMARY KEY AUTOINCREMENT, "
       "object_store_id INTEGER NOT NULL, "
       "data TEXT NOT NULL, "
-      "PRIMARY KEY (id), "
       "FOREIGN KEY (object_store_id) REFERENCES object_store(id) ON DELETE "
         "CASCADE"
     ");"
diff --git a/dom/indexedDB/IDBObjectStore.cpp b/dom/indexedDB/IDBObjectStore.cpp
index 1cb007a360c..6ddab0afc6c 100644
--- a/dom/indexedDB/IDBObjectStore.cpp
+++ b/dom/indexedDB/IDBObjectStore.cpp
@@ -146,6 +146,25 @@ public:
   PRUint16 GetSuccessResult(nsIWritableVariant* aResult);
 };
 
+class ClearHelper : public AsyncConnectionHelper
+{
+public:
+  ClearHelper(IDBTransaction* aTransaction,
+              IDBRequest* aRequest,
+              PRInt64 aObjectStoreID,
+              bool aAutoIncrement)
+  : AsyncConnectionHelper(aTransaction, aRequest), mOSID(aObjectStoreID),
+    mAutoIncrement(aAutoIncrement)
+  { }
+
+  PRUint16 DoDatabaseWork(mozIStorageConnection* aConnection);
+
+protected:
+  // In-params.
+  const PRInt64 mOSID;
+  const bool mAutoIncrement;
+};
+
 class OpenCursorHelper : public AsyncConnectionHelper
 {
 public:
@@ -920,7 +939,16 @@ IDBObjectStore::Add(const jsval &aValue,
     return NS_ERROR_OBJECT_IS_IMMUTABLE;
   }
 
-  jsval keyval = (aOptionalArgCount >= 1) ? aKey : JSVAL_VOID;
+  jsval keyval;
+  if (aOptionalArgCount >= 1) {
+    keyval = aKey;
+    if (mAutoIncrement && JSVAL_IS_NULL(keyval)) {
+      return NS_ERROR_ILLEGAL_VALUE;
+    }
+  }
+  else {
+    keyval = JSVAL_VOID;
+  }
 
   nsString jsonValue;
   Key key;
@@ -1032,6 +1060,32 @@ IDBObjectStore::Remove(nsIVariant* aKey,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+IDBObjectStore::Clear(nsIIDBRequest** _retval)
+{
+  NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
+
+  if (!mTransaction->TransactionIsOpen()) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mMode != nsIIDBTransaction::READ_WRITE) {
+    return NS_ERROR_OBJECT_IS_IMMUTABLE;
+  }
+
+  nsRefPtr<IDBRequest> request =
+    GenerateWriteRequest(mTransaction->ScriptContext(), mTransaction->Owner());
+  NS_ENSURE_TRUE(request, NS_ERROR_FAILURE);
+
+  nsRefPtr<ClearHelper> helper =
+    new ClearHelper(mTransaction, request, mId, !!mAutoIncrement);
+  nsresult rv = helper->DispatchToTransactionPool();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  request.forget(_retval);
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 IDBObjectStore::OpenCursor(nsIIDBKeyRange* aKeyRange,
                            PRUint16 aDirection,
@@ -1607,6 +1661,36 @@ RemoveHelper::GetSuccessResult(nsIWritableVariant* aResult)
   return OK;
 }
 
+PRUint16
+ClearHelper::DoDatabaseWork(mozIStorageConnection* aConnection)
+{
+  NS_PRECONDITION(aConnection, "Passed a null connection!");
+
+  nsCString table;
+  if (mAutoIncrement) {
+    table.AssignLiteral("ai_object_data");
+  }
+  else {
+    table.AssignLiteral("object_data");
+  }
+
+  nsCString query = NS_LITERAL_CSTRING("DELETE FROM ") + table +
+                    NS_LITERAL_CSTRING(" WHERE object_store_id = :osid");
+
+  nsCOMPtr<mozIStorageStatement> stmt = mTransaction->GetCachedStatement(query);
+  NS_ENSURE_TRUE(stmt, nsIIDBDatabaseException::UNKNOWN_ERR);
+
+  mozStorageStatementScoper scoper(stmt);
+
+  nsresult rv = stmt->BindInt64ByName(NS_LITERAL_CSTRING("osid"), mOSID);
+  NS_ENSURE_SUCCESS(rv, nsIIDBDatabaseException::UNKNOWN_ERR);
+
+  rv = stmt->Execute();
+  NS_ENSURE_SUCCESS(rv, nsIIDBDatabaseException::UNKNOWN_ERR);
+
+  return OK;
+}
+
 PRUint16
 OpenCursorHelper::DoDatabaseWork(mozIStorageConnection* aConnection)
 {
diff --git a/dom/indexedDB/nsIIDBObjectStore.idl b/dom/indexedDB/nsIIDBObjectStore.idl
index ecae8341c01..4b4fd9d65e7 100644
--- a/dom/indexedDB/nsIIDBObjectStore.idl
+++ b/dom/indexedDB/nsIIDBObjectStore.idl
@@ -89,6 +89,10 @@ interface nsIIDBObjectStore : nsISupports
   nsIIDBRequest
   remove(in nsIVariant key);
 
+  // Success fires IDBTransactionEvent, result == null
+  nsIIDBRequest
+  clear();
+
   // Success fires IDBTransactionEvent, result == IDBCursor or
   // IDBCursorPreloadedRequest if preload == true. result == null if no match.
   [optional_argc]
diff --git a/dom/indexedDB/test/Makefile.in b/dom/indexedDB/test/Makefile.in
index 41686e88b01..491802726ec 100644
--- a/dom/indexedDB/test/Makefile.in
+++ b/dom/indexedDB/test/Makefile.in
@@ -48,6 +48,7 @@ _TEST_FILES = \
   helpers.js \
   test_add_twice_failure.html \
   test_bad_keypath.html \
+  test_clear.html \
   test_create_index.html \
   test_create_objectStore.html \
   test_cursors.html \
diff --git a/dom/indexedDB/test/helpers.js b/dom/indexedDB/test/helpers.js
index 1b6f0e847fe..0c892d30133 100644
--- a/dom/indexedDB/test/helpers.js
+++ b/dom/indexedDB/test/helpers.js
@@ -23,6 +23,13 @@ function grabEventAndContinueHandler(event)
   testGenerator.send(event);
 }
 
+function continueToNextStep()
+{
+  SimpleTest.executeSoon(function() {
+    testGenerator.next();
+  });
+}
+
 function errorHandler(event)
 {
   ok(false, "indexedDB error (" + event.code + "): " + event.message);
diff --git a/dom/indexedDB/test/test_clear.html b/dom/indexedDB/test/test_clear.html
new file mode 100644
index 00000000000..f5a1e393024
--- /dev/null
+++ b/dom/indexedDB/test/test_clear.html
@@ -0,0 +1,113 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html>
+<head>
+  <title>Indexed Database Property Test</title>
+
+  <script type="text/javascript" src="/MochiKit/packed.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+
+  <script type="text/javascript;version=1.7">
+    function testSteps()
+    {
+      const READ_WRITE = Components.interfaces.nsIIDBTransaction.READ_WRITE;
+
+      const name = window.location.pathname;
+      const description = "My Test Database";
+      const entryCount = 1000;
+
+      let request = moz_indexedDB.open(name, description);
+      request.onerror = errorHandler;
+      request.onsuccess = grabEventAndContinueHandler;
+      let event = yield;
+
+      let db = event.result;
+
+      request = db.createObjectStore("foo", "", true);
+      request.onerror = errorHandler;
+      request.onsuccess = grabEventAndContinueHandler;
+      let event = yield;
+
+      event.transaction.oncomplete = continueToNextStep;
+
+      let objectStore = event.result;
+
+      let firstKey;
+      for (let i = 0; i < entryCount; i++) {
+        request = objectStore.add({});
+        request.onerror = errorHandler;
+        if (!i) {
+          request.onsuccess = function(event) {
+            firstKey = event.result;
+          };
+        }
+      }
+      yield;
+
+      isnot(firstKey, undefined, "got first key");
+
+      let seenEntryCount = 0;
+
+      request = db.objectStore("foo").openCursor();
+      request.onerror = errorHandler;
+      request.onsuccess = function(event) {
+        let cursor = event.result;
+        if (cursor) {
+          seenEntryCount++;
+          cursor.continue();
+        }
+        else {
+          continueToNextStep();
+        }
+      }
+      yield;
+
+      is(seenEntryCount, entryCount, "Correct entry count");
+
+      try {
+        db.objectStore("foo").clear();
+        ok(false, "clear should throw on READ_ONLY transactions");
+      }
+      catch (e) {
+        ok(true, "clear should throw on READ_ONLY transactions");
+      }
+
+      request = db.objectStore("foo", READ_WRITE).clear();
+      request.onerror = errorHandler;
+      request.onsuccess = grabEventAndContinueHandler;
+      event = yield;
+
+      ok(event.result === null, "Correct event.result");
+
+      request = db.objectStore("foo").openCursor();
+      request.onerror = errorHandler;
+      request.onsuccess = function(event) {
+        let cursor = event.result;
+        if (cursor) {
+          ok(false, "Shouldn't have any entries");
+        }
+        continueToNextStep();
+      }
+      yield;
+
+      request = db.objectStore("foo", READ_WRITE).add({});
+      request.onerror = errorHandler;
+      request.onsuccess = grabEventAndContinueHandler;
+      event = yield;
+
+      isnot(event.result, firstKey, "Got a different key");
+
+      finishTest();
+      yield;
+    }
+  </script>
+  <script type="text/javascript;version=1.7" src="helpers.js"></script>
+
+</head>
+
+<body onload="runTest();"></body>
+
+</html>