Until Twitter Bootstrap v3, I would have recommend that you use dotLess to compile and bundle your LESS files. However, it is now a known issue that the current build of dotLess does not support Bootstrap 3, or more specifically that it does not support LESS 1.4; and worse yet, there is no fix in sight.
So, how can you use Bootstrap LESS with MVC?
I recommend using BundleTransformer. It is an amazingly feature rich set of extensions for System.Web.Optimization. The BundleTransformer.Less extension provides easy to use LESS transformations (already up to LESS 1.5) and bundling support that wires up straight into your pre-existing BundleCollection configuration. For more information about everything that BundleTransformer has to offer, check out this article.
Now here is how you setup Bootstrap 3 and BundleTransformer for ASP.NET:
