diff --git a/services/common/storageservice.js b/services/common/storageservice.js
index efe5f9b822cf..18e4acb08a98 100644
--- a/services/common/storageservice.js
+++ b/services/common/storageservice.js
@@ -870,9 +870,12 @@ StorageServiceRequest.prototype = {
         return;
       }
 
-      if (response.status == 503) {
+      if (response.status >= 500 && response.status <= 599) {
+        this._log.error(response.status + " seen from server!");
         this._error = new StorageServiceRequestError();
-        this._error.server = new Error("503 Received.");
+        this._error.server = new Error(response.status + " status code.");
+        callOnComplete();
+        return;
       }
 
       callOnComplete();
@@ -1084,15 +1087,21 @@ StorageCollectionGetRequest.prototype = {
 function StorageCollectionSetRequest() {
   StorageServiceRequest.call(this);
 
-  this._lines = [];
-  this._size  = 0;
+  this.size = 0;
 
-  this.successfulIDs = new Set();
-  this.failures      = new Map();
+  // TODO Bug 775781 convert to Set and Map once iterable.
+  this.successfulIDs = [];
+  this.failures      = {};
+
+  this._lines = [];
 }
 StorageCollectionSetRequest.prototype = {
   __proto__: StorageServiceRequest.prototype,
 
+  get count() {
+    return this._lines.length;
+  },
+
   /**
    * Add a BasicStorageObject to this request.
    *
@@ -1112,33 +1121,384 @@ StorageCollectionSetRequest.prototype = {
       throw new Error("Passed BSO must have id defined.");
     }
 
-    let line = JSON.stringify(bso).replace("\n", "\u000a");
+    this.addLine(JSON.stringify(bso));
+  },
 
+  /**
+   * Add a BSO (represented by its serialized newline-delimited form).
+   *
+   * You probably shouldn't use this. It is used for batching.
+   */
+  addLine: function addLine(line) {
     // This is off by 1 in the larger direction. We don't care.
-    this._size += line.length + "\n".length;
+    this.size += line.length + 1;
     this._lines.push(line);
   },
 
   _onDispatch: function _onDispatch() {
     this._data = this._lines.join("\n");
+    this.size = this._data.length;
   },
 
   _completeParser: function _completeParser(response) {
     let result = JSON.parse(response.body);
 
     for (let id of result.success) {
-      this.successfulIDs.add(id);
+      this.successfulIDs.push(id);
     }
 
     this.allSucceeded = true;
 
-    for (let [id, reasons] in result.failed) {
+    for (let [id, reasons] in Iterator(result.failed)) {
       this.failures[id] = reasons;
       this.allSucceeded = false;
     }
   },
 };
 
+/**
+ * Represents a batch upload of BSOs to an individual collection.
+ *
+ * This is a more intelligent way to upload may BSOs to the server. It will
+ * split the uploaded data into multiple requests so size limits, etc aren't
+ * exceeded.
+ *
+ * Once a client obtains an instance of this type, it calls `addBSO` for each
+ * BSO to be uploaded. When the client is done providing BSOs to be uploaded,
+ * it calls `finish`. When `finish` is called, no more BSOs can be added to the
+ * batch. When all requests created from this batch have finished, the callback
+ * provided to `finish` will be invoked.
+ *
+ * Clients can also explicitly flush pending outgoing BSOs via `flush`. This
+ * allows callers to control their own batching/chunking.
+ *
+ * Interally, this maintains a queue of StorageCollectionSetRequest to be
+ * issued. At most one request is allowed to be in-flight at once. This is to
+ * avoid potential conflicts on the server. And, in the case of conditional
+ * requests, it prevents requests from being declined due to the server being
+ * updated by another request issued by us.
+ *
+ * If a request errors for any reason, all queued uploads are abandoned and the
+ * `finish` callback is invoked as soon as possible. The `successfulIDs` and
+ * `failures` properties will contain data from all requests that had this
+ * response data. In other words, the IDs have BSOs that were never sent to the
+ * server are not lumped in to either property.
+ *
+ * Requests can be made conditional by setting `locallyModifiedVersion` to the
+ * most recent version of server data. As responses from the server are seen,
+ * the last server version is carried forward to subsequent requests.
+ *
+ * The server version from the last request is available in the
+ * `serverModifiedVersion` property. It should only be accessed during or
+ * after the callback passed to `finish`.
+ *
+ * @param client
+ *        (StorageServiceClient) Client instance to use for uploading.
+ *
+ * @param collection
+ *        (string) Collection the batch operation will upload to.
+ */
+function StorageCollectionBatchedSet(client, collection) {
+  this.client     = client;
+  this.collection = collection;
+
+  this._log = client._log;
+
+  this.locallyModifiedVersion = null;
+  this.serverModifiedVersion  = null;
+
+  // TODO Bug 775781 convert to Set and Map once iterable.
+  this.successfulIDs = [];
+  this.failures      = {};
+
+  // Request currently being populated.
+  this._stagingRequest = client.setBSOs(this.collection);
+
+  // Requests ready to be sent over the wire.
+  this._outgoingRequests = [];
+
+  // Whether we are waiting for a response.
+  this._requestInFlight = false;
+
+  this._onFinishCallback = null;
+  this._finished         = false;
+  this._errorEncountered = false;
+}
+StorageCollectionBatchedSet.prototype = {
+  /**
+   * Add a BSO to be uploaded as part of this batch.
+   */
+  addBSO: function addBSO(bso) {
+    if (this._errorEncountered) {
+      return;
+    }
+
+    let line = JSON.stringify(bso);
+
+    if (line.length > this.client.REQUEST_SIZE_LIMIT) {
+      throw new Error("BSO is larger than allowed limit: " + line.length +
+                      " > " + this.client.REQUEST_SIZE_LIMIT);
+    }
+
+    if (this._stagingRequest.size + line.length > this.client.REQUEST_SIZE_LIMIT) {
+      this._log.debug("Sending request because payload size would be exceeded");
+      this._finishStagedRequest();
+
+      this._stagingRequest.addLine(line);
+      return;
+    }
+
+    // We are guaranteed to fit within size limits.
+    this._stagingRequest.addLine(line);
+
+    if (this._stagingRequest.count >= this.client.REQUEST_BSO_COUNT_LIMIT) {
+      this._log.debug("Sending request because BSO count threshold reached.");
+      this._finishStagedRequest();
+      return;
+    }
+  },
+
+  finish: function finish(cb) {
+    if (this._finished) {
+      throw new Error("Batch request has already been finished.");
+    }
+
+    this.flush();
+
+    this._onFinishCallback = cb;
+    this._finished = true;
+    this._stagingRequest = null;
+  },
+
+  flush: function flush() {
+    if (this._finished) {
+      throw new Error("Batch request has been finished.");
+    }
+
+    if (!this._stagingRequest.count) {
+      return;
+    }
+
+    this._finishStagedRequest();
+  },
+
+  _finishStagedRequest: function _finishStagedRequest() {
+    this._outgoingRequests.push(this._stagingRequest);
+    this._sendOutgoingRequest();
+    this._stagingRequest = this.client.setBSOs(this.collection);
+  },
+
+  _sendOutgoingRequest: function _sendOutgoingRequest() {
+    if (this._requestInFlight || this._errorEncountered) {
+      return;
+    }
+
+    if (!this._outgoingRequests.length) {
+      return;
+    }
+
+    let request = this._outgoingRequests.shift();
+
+    if (this.locallyModifiedVersion) {
+      request.locallyModifiedVersion = this.locallyModifiedVersion;
+    }
+
+    request.dispatch(this._onBatchComplete.bind(this));
+    this._requestInFlight = true;
+  },
+
+  _onBatchComplete: function _onBatchComplete(error, request) {
+    this._requestInFlight = false;
+
+    this.serverModifiedVersion = request.serverTime;
+
+    // Only update if we had a value before. Otherwise, this breaks
+    // unconditional requests!
+    if (this.locallyModifiedVersion) {
+      this.locallyModifiedVersion = request.serverTime;
+    }
+
+    for (let id of request.successfulIDs) {
+      this.successfulIDs.push(id);
+    }
+
+    for (let [id, reason] in Iterator(request.failures)) {
+      this.failures[id] = reason;
+    }
+
+    if (request.error) {
+      this._errorEncountered = true;
+    }
+
+    this._checkFinish();
+  },
+
+  _checkFinish: function _checkFinish() {
+    if (this._outgoingRequests.length && !this._errorEncountered) {
+      this._sendOutgoingRequest();
+      return;
+    }
+
+    if (!this._onFinishCallback) {
+      return;
+    }
+
+    try {
+      this._onFinishCallback(this);
+    } catch (ex) {
+      this._log.warn("Exception when calling finished callback: " +
+                     CommonUtils.exceptionStr(ex));
+    }
+  },
+};
+Object.freeze(StorageCollectionBatchedSet.prototype);
+
+/**
+ * Manages a batch of BSO deletion requests.
+ *
+ * A single instance of this virtual request allows deletion of many individual
+ * BSOs without having to worry about server limits.
+ *
+ * Instances are obtained by calling `deleteBSOsBatching` on
+ * StorageServiceClient.
+ *
+ * Usage is roughly the same as StorageCollectionBatchedSet. Callers obtain
+ * an instance and select individual BSOs for deletion by calling `addID`.
+ * When the caller is finished marking BSOs for deletion, they call `finish`
+ * with a callback which will be invoked when all deletion requests finish.
+ *
+ * When the finished callback is invoked, any encountered errors will be stored
+ * in the `errors` property of this instance (which is passed to the callback).
+ * This will be an empty array if no errors were encountered. Else, it will
+ * contain the errors from the `onComplete` handler of request instances. The
+ * set of succeeded and failed IDs is not currently available.
+ *
+ * Deletes can be made conditional by setting `locallyModifiedVersion`. The
+ * behavior is the same as request types. The only difference is that the
+ * updated version from the server as a result of requests is carried forward
+ * to subsequent requests.
+ *
+ * The server version from the last request is stored in the
+ * `serverModifiedVersion` property. It is not safe to access this until the
+ * callback from `finish`.
+ *
+ * Like StorageCollectionBatchedSet, requests are issued serially to avoid
+ * race conditions on the server.
+ *
+ * @param client
+ *        (StorageServiceClient) Client request is associated with.
+ * @param collection
+ *        (string) Collection being operated on.
+ */
+function StorageCollectionBatchedDelete(client, collection) {
+  this.client     = client;
+  this.collection = collection;
+
+  this._log = client._log;
+
+  this.locallyModifiedVersion = null;
+  this.serverModifiedVersion  = null;
+  this.errors                 = [];
+
+  this._pendingIDs          = [];
+  this._requestInFlight     = false;
+  this._finished            = false;
+  this._finishedCallback    = null;
+}
+StorageCollectionBatchedDelete.prototype = {
+  addID: function addID(id) {
+    if (this._finished) {
+      throw new Error("Cannot add IDs to a finished instance.");
+    }
+
+    // If we saw errors already, don't do any work. This is an optimization
+    // and isn't strictly required, as _sendRequest() should no-op.
+    if (this.errors.length) {
+      return;
+    }
+
+    this._pendingIDs.push(id);
+
+    if (this._pendingIDs.length >= this.client.REQUEST_BSO_DELETE_LIMIT) {
+      this._sendRequest();
+    }
+  },
+
+  /**
+   * Finish this batch operation.
+   *
+   * No more IDs can be added to this operation. Existing IDs are flushed as
+   * a request. The passed callback will be called when all requests have
+   * finished.
+   */
+  finish: function finish(cb) {
+    if (this._finished) {
+      throw new Error("Batch delete instance has already been finished.");
+    }
+
+    this._finished = true;
+    this._finishedCallback = cb;
+
+    if (this._pendingIDs.length) {
+      this._sendRequest();
+    }
+  },
+
+  _sendRequest: function _sendRequest() {
+    // Only allow 1 active request at a time and don't send additional
+    // requests if one has failed.
+    if (this._requestInFlight || this.errors.length) {
+      return;
+    }
+
+    let ids = this._pendingIDs.splice(0, this.client.REQUEST_BSO_DELETE_LIMIT);
+    let request = this.client.deleteBSOs(this.collection, ids);
+
+    if (this.locallyModifiedVersion) {
+      request.locallyModifiedVersion = this.locallyModifiedVersion;
+    }
+
+    request.dispatch(this._onRequestComplete.bind(this));
+    this._requestInFlight = true;
+  },
+
+  _onRequestComplete: function _onRequestComplete(error, request) {
+    this._requestInFlight = false;
+
+    if (error) {
+      // We don't currently track metadata of what failed. This is an obvious
+      // feature that could be added.
+      this._log.warn("Error received from server: " + error);
+      this.errors.push(error);
+    }
+
+    this.serverModifiedVersion = request.serverTime;
+
+    // If performing conditional requests, carry forward the new server version
+    // so subsequent conditional requests work.
+    if (this.locallyModifiedVersion) {
+      this.locallyModifiedVersion = request.serverTime;
+    }
+
+    if (this._pendingIDs.length && !this.errors.length) {
+      this._sendRequest();
+      return;
+    }
+
+    if (!this._finishedCallback) {
+      return;
+    }
+
+    try {
+      this._finishedCallback(this);
+    } catch (ex) {
+      this._log.warn("Exception when invoking finished callback: " +
+                     CommonUtils.exceptionStr(ex));
+    }
+  },
+};
+Object.freeze(StorageCollectionBatchedDelete.prototype);
+
 /**
  * Construct a new client for the SyncStorage API, version 2.0.
  *
@@ -1195,6 +1555,27 @@ StorageServiceClient.prototype = {
    */
   userAgent: "StorageServiceClient",
 
+  /**
+   * Maximum size of entity bodies.
+   *
+   * TODO this should come from the server somehow. See bug 769759.
+   */
+  REQUEST_SIZE_LIMIT: 512000,
+
+  /**
+   * Maximum number of BSOs in requests.
+   *
+   * TODO this should come from the server somehow. See bug 769759.
+   */
+  REQUEST_BSO_COUNT_LIMIT: 100,
+
+  /**
+   * Maximum number of BSOs that can be deleted in a single DELETE.
+   *
+   * TODO this should come from the server. See bug 769759.
+   */
+  REQUEST_BSO_DELETE_LIMIT: 100,
+
   _baseURI: null,
   _log: null,
 
@@ -1584,11 +1965,9 @@ StorageServiceClient.prototype = {
    * has additional functions and properties specific to this operation. See
    * its documentation for more.
    *
-   * Future improvement: support streaming of uploaded records. Currently, data
-   * is buffered in the client before going over the wire. Ideally, we'd support
-   * sending over the wire as soon as data is available. This will require
-   * support in RESTRequest, which doesn't support streaming on requests, only
-   * responses.
+   * Most consumers interested in submitting multiple BSOs to the server will
+   * want to use `setBSOsBatching` instead. That API intelligently splits up
+   * requests as necessary, etc.
    *
    * Example usage:
    *
@@ -1635,6 +2014,30 @@ StorageServiceClient.prototype = {
     return request;
   },
 
+  /**
+   * This is a batching variant of setBSOs.
+   *
+   * Whereas `setBSOs` is a 1:1 mapping between function calls and HTTP
+   * requests issued, this one is a 1:N mapping. It will intelligently break
+   * up outgoing BSOs into multiple requests so size limits, etc aren't
+   * exceeded.
+   *
+   * Please see the documentation for `StorageCollectionBatchedSet` for
+   * usage info.
+   *
+   * @param collection
+   *        (string) Collection to operate on.
+   * @return
+   *        (StorageCollectionBatchedSet) Batched set instance.
+   */
+  setBSOsBatching: function setBSOsBatching(collection) {
+    if (!collection) {
+      throw new Error("collection argument must be defined.");
+    }
+
+    return new StorageCollectionBatchedSet(this, collection);
+  },
+
   /**
    * Deletes a single BSO from a collection.
    *
@@ -1670,6 +2073,10 @@ StorageServiceClient.prototype = {
    * The request can be made conditional by setting `locallyModifiedVersion`
    * on the returned request instance.
    *
+   * If the number of BSOs to delete is potentially large, it is preferred to
+   * use `deleteBSOsBatching`. That API automatically splits the operation into
+   * multiple requests so server limits aren't exceeded.
+   *
    * @param collection
    *        (string) Name of collection to delete BSOs from.
    * @param ids
@@ -1688,6 +2095,24 @@ StorageServiceClient.prototype = {
     });
   },
 
+  /**
+   * Bulk deletion of BSOs with no size limit.
+   *
+   * This allows a large amount of BSOs to be deleted easily. It will formulate
+   * multiple `deleteBSOs` queries so the client does not exceed server limits.
+   *
+   * @param collection
+   *        (string) Name of collection to delete BSOs from.
+   * @return StorageCollectionBatchedDelete
+   */
+  deleteBSOsBatching: function deleteBSOsBatching(collection) {
+    if (!collection) {
+      throw new Error("collection argument must be defined.");
+    }
+
+    return new StorageCollectionBatchedDelete(this, collection);
+  },
+
   /**
    * Deletes a single collection from the server.
    *
diff --git a/services/common/tests/unit/test_storageservice_client.js b/services/common/tests/unit/test_storageservice_client.js
index a9eea90dd779..8cccce5ee9e3 100644
--- a/services/common/tests/unit/test_storageservice_client.js
+++ b/services/common/tests/unit/test_storageservice_client.js
@@ -12,7 +12,11 @@ function run_test() {
   run_next_test();
 }
 
-function getEmptyServer(user="765", password="password") {
+function getRandomUser() {
+  return "" + (Math.floor(Math.random() * 100000) + 1);
+}
+
+function getEmptyServer(user=getRandomUser(), password="password") {
   let users = {};
   users[user] = password;
 
@@ -23,7 +27,7 @@ function getEmptyServer(user="765", password="password") {
   });
 }
 
-function getClient(user="765", password="password") {
+function getClient(user=getRandomUser(), password="password") {
   let client = new StorageServiceClient(BASE_URI + "/" + user);
   client.addListener({
     onDispatch: function onDispatch(request) {
@@ -35,7 +39,7 @@ function getClient(user="765", password="password") {
   return client;
 }
 
-function getServerAndClient(user="765", password="password") {
+function getServerAndClient(user=getRandomUser(), password="password") {
   let server = getEmptyServer(user, password);
   let client = getClient(user, password);
 
@@ -644,9 +648,9 @@ add_test(function test_set_bsos_simple() {
     do_check_null(error);
 
     let successful = req.successfulIDs;
-    do_check_eq(successful.size(), 2);
-    do_check_true(successful.has(bso0.id));
-    do_check_true(successful.has(bso1.id));
+    do_check_eq(successful.length, 2);
+    do_check_eq(successful.indexOf(bso0.id), 0);
+    do_check_true(successful.indexOf(bso1.id), 1);
 
     server.stop(run_next_test);
   });
@@ -701,7 +705,7 @@ add_test(function test_set_bsos_newline() {
 
   request.dispatch(function onComplete(error, request) {
     do_check_null(error);
-    do_check_eq(request.successfulIDs.size(), 2);
+    do_check_eq(request.successfulIDs.length, 2);
 
     let coll = user.collection("testcoll");
     do_check_eq(coll.bso("bso0").payload, bso0.payload);
@@ -965,3 +969,409 @@ add_test(function test_network_error_listener() {
     run_next_test();
   });
 });
+
+add_test(function test_batching_set_too_large() {
+  _("Ensure we throw when attempting to add a BSO that is too large to fit.");
+
+  let [server, client, username] = getServerAndClient();
+
+  let request = client.setBSOsBatching("testcoll");
+  let payload = "";
+
+  // The actual length of the payload is a little less. But, this ensures we
+  // exceed it.
+  for (let i = 0; i < client.REQUEST_SIZE_LIMIT; i++) {
+    payload += i;
+  }
+
+  let bso = new BasicStorageObject("bso");
+  bso.payload = payload;
+  do_check_throws(function add() { request.addBSO(bso); });
+
+  server.stop(run_next_test);
+});
+
+add_test(function test_batching_set_basic() {
+  _("Ensure batching set works with single requests.");
+
+  let [server, client, username] = getServerAndClient();
+
+  let request = client.setBSOsBatching("testcoll");
+  for (let i = 0; i < 10; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "payload" + i;
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(request.successfulIDs.length, 10);
+
+    let collection = server.user(username).collection("testcoll");
+    do_check_eq(collection.timestamp, request.serverModifiedVersion);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_batch_count() {
+  _("Ensure multiple outgoing request batching works when count is exceeded.");
+
+  let [server, client, username] = getServerAndClient();
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let request = client.setBSOsBatching("testcoll");
+  for (let i = 1; i <= 300; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "XXXXXXX";
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(request.successfulIDs.length, 300);
+    do_check_eq(requestCount, 3);
+
+    let collection = server.user(username).collection("testcoll");
+    do_check_eq(collection.timestamp, request.serverModifiedVersion);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_batch_size() {
+  _("Ensure outgoing requests batch when size is exceeded.");
+
+  let [server, client, username] = getServerAndClient();
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  };
+
+  let limit = client.REQUEST_SIZE_LIMIT;
+
+  let request = client.setBSOsBatching("testcoll");
+
+  // JavaScript: Y U NO EASY REPETITION FUNCTIONALITY?
+  let data = [];
+  for (let i = (limit / 2) - 100; i; i -= 1) {
+    data.push("X");
+  }
+
+  let payload = data.join("");
+
+  for (let i = 0; i < 4; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = payload;
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(request.successfulIDs.length, 4);
+    do_check_eq(requestCount, 2);
+
+    let collection = server.user(username).collection("testcoll");
+    do_check_eq(collection.timestamp, request.serverModifiedVersion);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_flush() {
+  _("Ensure flushing batch sets works.");
+
+  let [server, client, username] = getServerAndClient();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let request = client.setBSOsBatching("testcoll");
+  for (let i = 1; i < 101; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "foo";
+    request.addBSO(bso);
+
+    if (i % 10 == 0) {
+      request.flush();
+    }
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(request.successfulIDs.length, 100);
+    do_check_eq(requestCount, 10);
+
+    let collection = server.user(username).collection("testcoll");
+    do_check_eq(collection.timestamp, request.serverModifiedVersion);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_conditional_success() {
+  _("Ensure conditional requests for batched sets work properly.");
+
+  let [server, client, username] = getServerAndClient();
+
+  let collection = server.user(username).createCollection("testcoll");
+
+  let lastServerVersion = Date.now();
+  collection.insertBSO(new ServerBSO("foo", "bar", lastServerVersion));
+  do_check_eq(collection.timestamp, lastServerVersion);
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let request = client.setBSOsBatching("testcoll");
+  request.locallyModifiedVersion = collection.timestamp;
+
+  for (let i = 1; i < 251; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "foo" + i;
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 3);
+
+    do_check_eq(collection.timestamp, request.serverModifiedVersion);
+    do_check_eq(collection.timestamp, request.locallyModifiedVersion);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_initial_failure() {
+  _("Ensure that an initial request failure setting BSOs is handled properly.");
+
+  let [server, client, username] = getServerAndClient();
+
+  let collection = server.user(username).createCollection("testcoll");
+  collection.timestamp = Date.now();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let request = client.setBSOsBatching("testcoll");
+  request.locallyModifiedVersion = collection.timestamp - 1;
+
+  for (let i = 1; i < 250; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "foo" + i;
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 1);
+
+    do_check_eq(request.successfulIDs.length, 0);
+    do_check_eq(Object.keys(request.failures).length, 0);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batching_set_subsequent_failure() {
+  _("Ensure a non-initial failure during batching set is handled properly.");
+
+  let [server, client, username] = getServerAndClient();
+  let collection = server.user(username).createCollection("testcoll");
+  collection.timestamp = Date.now();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+
+    if (requestCount == 1) {
+      return;
+    }
+
+    collection.timestamp++;
+  }
+
+  let request = client.setBSOsBatching("testcoll");
+  request.locallyModifiedVersion = collection.timestamp;
+
+  for (let i = 0; i < 250; i++) {
+    let bso = new BasicStorageObject("bso" + i);
+    bso.payload = "foo" + i;
+    request.addBSO(bso);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 2);
+    do_check_eq(request.successfulIDs.length, 100);
+    do_check_eq(Object.keys(request.failures).length, 0);
+
+    server.stop(run_next_test);
+  });
+});
+
+function getBatchedDeleteData(collection="testcoll") {
+  let [server, client, username] = getServerAndClient();
+
+  let serverBSOs = {};
+  for (let i = 1000; i; i -= 1) {
+    serverBSOs["bso" + i] = new ServerBSO("bso" + i, "payload" + i);
+  }
+
+  let user = server.user(username);
+  user.createCollection(collection, serverBSOs);
+
+  return [server, client, username, collection];
+}
+
+add_test(function test_batched_delete_single() {
+  _("Ensure batched delete with single request works.");
+
+  let [server, client, username, collection] = getBatchedDeleteData();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount += 1;
+  }
+
+  let request = client.deleteBSOsBatching(collection);
+  for (let i = 1; i < 51; i += 1) {
+    request.addID("bso" + i);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 1);
+    do_check_eq(request.errors.length, 0);
+
+    let coll = server.user(username).collection(collection);
+    do_check_eq(coll.count(), 950);
+
+    do_check_eq(request.serverModifiedVersion, coll.timestamp);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batched_delete_multiple() {
+  _("Ensure batched delete splits requests properly.");
+
+  let [server, client, username, collection] = getBatchedDeleteData();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount += 1;
+  }
+
+  let request = client.deleteBSOsBatching(collection);
+  for (let i = 1; i < 251; i += 1) {
+    request.addID("bso" + i);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 3);
+    do_check_eq(request.errors.length, 0);
+
+    let coll = server.user(username).collection(collection);
+    do_check_eq(coll.count(), 750);
+
+    do_check_eq(request.serverModifiedVersion, coll.timestamp);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batched_delete_conditional_success() {
+  _("Ensure conditional batched delete all work.");
+
+  let [server, client, username, collection] = getBatchedDeleteData();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let serverCollection = server.user(username).collection(collection);
+  let initialTimestamp = serverCollection.timestamp;
+
+  let request = client.deleteBSOsBatching(collection);
+  request.locallyModifiedVersion = initialTimestamp;
+
+  for (let i = 1; i < 251; i += 1) {
+    request.addID("bso" + 1);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 3);
+    do_check_eq(request.errors.length, 0);
+
+    do_check_true(request.locallyModifiedVersion > initialTimestamp);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batched_delete_conditional_initial_failure() {
+  _("Ensure conditional batched delete failure on initial request works.");
+
+  // The client needs to issue multiple requests but the first one was
+  // rejected. The client should only issue that initial request.
+  let [server, client, username, collection] = getBatchedDeleteData();
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+  }
+
+  let serverCollection = server.user(username).collection(collection);
+  let request = client.deleteBSOsBatching(collection);
+  request.locallyModifiedVersion = serverCollection.timestamp - 1;
+
+  for (let i = 1; i < 251; i += 1) {
+    request.addID("bso" + i);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 1);
+    do_check_eq(request.errors.length, 1);
+
+    server.stop(run_next_test);
+  });
+});
+
+add_test(function test_batched_delete_conditional_subsequent_failure() {
+  _("Ensure conditional batched delete failure on non-initial request.");
+
+  let [server, client, username, collection] = getBatchedDeleteData();
+
+  let serverCollection = server.user(username).collection(collection);
+
+  let requestCount = 0;
+  server.callback.onRequest = function onRequest() {
+    requestCount++;
+
+    if (requestCount <= 1) {
+      return;
+    }
+
+    // Advance collection's timestamp on subsequent requests so request is
+    // rejected.
+    serverCollection.timestamp++;
+  }
+
+  let request = client.deleteBSOsBatching(collection);
+  request.locallyModifiedVersion = serverCollection.timestamp;
+
+  for (let i = 1; i < 251; i += 1) {
+    request.addID("bso" + i);
+  }
+
+  request.finish(function onFinish(request) {
+    do_check_eq(requestCount, 2);
+    do_check_eq(request.errors.length, 1);
+
+    server.stop(run_next_test);
+  });
+});