So, not so much a bench marking tool as a load generation tool. HammerDB is one of the preferred approaches. But, if you want to simulate load, you could get a copy of SQL Server 2012 and use the Distributed Replay tool. That lets you replay a captured trace, a great way to simulate your production environment. The old company Quest used to have a load simulation tool. They're now Dell Software. I'm not sure if the tool is still available, but it would be a place to start looking.