timing ember-cli-mocha unit tests

We are trying to benchmark our mocha unit tests in our Ember application. We want to know how long each test takes in milliseconds to be able to optimize the tests that take the longest. How can we time each unit test or output the slowest unit tests using ember-cli-mocha? We prefer not to manually watch the tests run. There are a few thousand tests and we'd like to continue to monitor tests as part of our CI process.