Testing Elastic Beanstalk Website

I have setup a website with elastic beanstalk on Amazon and i would like to test how many hits it can manage before it fails.

I would like to see it auto scaling the load balancers kicking in etc..

What software can i use to run the tests as i would like to see what it can handle so i can tell my client.

New application version was deployed to running EC2 instances.

I have taken a look at some applications for benchmarking but cannot seems to find anything that runs the tests i am after there is obviously something out there that i dont know about yet.

Please help