diff --git a/tools/meteor.js b/tools/meteor.js
index 328a25a02b..929be58176 100644
--- a/tools/meteor.js
+++ b/tools/meteor.js
@@ -1120,6 +1120,10 @@ Fiber(function () {
         .boolean('production')
         .describe('production', 'Run in production mode. Minify and bundle CSS and JS files.')
         .boolean('once') // See #Once
+        // To ensure that QA covers both PollingObserveDriver and
+        // OplogObserveDriver, this option disables oplog for tests.
+        // (It still creates a replset, it just doesn't do oplog tailing.)
+        .boolean('disable-oplog')
         .describe('settings',  'Set optional data for Meteor.settings on the server')
         .usage(
           "Usage: meteor test-packages [--release <release>] [options] [package...]\n" +
@@ -1201,6 +1205,7 @@ Fiber(function () {
           port: argv.port,
           minify: argv.production,
           once: argv.once,
+          disableOplog: argv['disable-oplog'],
           testPackages: testPackages,
           settingsFile: argv.settings,
           banner: "Tests"
diff --git a/tools/run.js b/tools/run.js
index 52a90ed192..cd4da15890 100644
--- a/tools/run.js
+++ b/tools/run.js
@@ -243,7 +243,8 @@ var startServer = function (options) {
 
   env.PORT = options.innerPort;
   env.MONGO_URL = options.mongoUrl;
-  env.MONGO_OPLOG_URL = options.oplogUrl;
+  if (options.oplogUrl)
+    env.MONGO_OPLOG_URL = options.oplogUrl;
   env.ROOT_URL = options.rootUrl;
   if (options.settings)
     env.METEOR_SETTINGS = options.settings;
@@ -417,9 +418,12 @@ exports.run = function (context, options) {
   // Allow people to specify an MONGO_OPLOG_URL override. If someone specifies a
   // MONGO_URL but not an MONGO_OPLOG_URL, disable the oplog. If neither is
   // specified, use the default internal mongo oplog.
-  var oplogUrl = process.env.MONGO_OPLOG_URL ||
-        (process.env.MONGO_URL ? undefined
-         : "mongodb://127.0.0.1:" + mongoPort + "/local");
+  var oplogUrl = undefined;
+  if (!options.disableOplog) {
+    oplogUrl = process.env.MONGO_OPLOG_URL ||
+      (process.env.MONGO_URL ? undefined
+       : "mongodb://127.0.0.1:" + mongoPort + "/local");
+  }
   var firstRun = true;
 
   var serverHandle;