babili to transform entire bundle

I have the following browserify fn call:

browserify({require: [
    'blah',
    'blah2',
    './bootstrap-datepicker'
]})
.require( './countdown', {expose: 'countdown'})
.transform(babelify.configure({ presets: ['es2015', 'babili'], sourceMaps: false }))
.bundle()
.pipe(jetpack.createWriteStream('build/vendor.js'))

For some reason it is only minifying the last library in the bundle. I've been trying to figure out how to run it on the whole bundle. Is there a way to do this given the current configuration? Or do I have to wait until the bundle is done and run babili on it separately? Would it be at all possible to provide an example of this working?

FYI - also posted the question here - http://stackoverflow.com/questions/43679538/minify-every-file-in-the-bundle-with-babili

Apologies if this is redundant, but I just can't seem to find any examples of what I need.