Node.js posting a large request using request module hangs

I am using the node.js request module to post a large POST request (~150MB) to a REST service. For any request bigger than about 30MB, it seems to hang. My guess is that it is doing some naive JSON.stringify()ing to the data instead of streaming it, and once it gets large enough to hit swap, it just becomes very slow.

This is what my request looks like:

request({
  uri: url
  method: 'post',
  json: args, // args is a 150MB json object
}, function(err, resp, body) {
  // do something
});

The same request made using angularjs's $http from within a browser works in less than a minute, so I know it's the cilent and not the server.

Is there an easy way to fix this?