It looks like Bundling and Minification are no longer built into MVC 6 since there is no more App_Start and Bundle.Config.
Is this going to be the case after final release?
I'm guessing Grunt should be used since that seems to be baked into Visual Studio 2015.
UPDATE: It looks like Microsoft has switched to Gulp instead of Grunt in RC1.
Grunt is the recommended approach in ASP.NET 5 applications. There are no plans to build a system like the previous ASP.NET Bundling and Minification (Optimization) system.