Not everything in the Constitution is good.

Libertarians like to say that the government ought to return to its Constitutional limits - which, at a minimum, is true. But many powers granted the government in the Constitution are fundamentally opposed to libertarian values - a Libertarian government ought to not only remain inside the Constitution, but retreat further inside of it to maximize the freedom of the governed. Here are a few passages which cause concern:

The Senators and Representatives shall...in all Cases, except Treason, Felony and Breach of the Peace, be privileged from Arrest during their Attendance at the Session of their respective Houses, and in going to and returning from the same; and for any Speech or Debate in either House, they shall not be questioned in any other Place.

That's immunity from the law, which shouldn't be granted to anybody.

To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes

Free trade isn't prescribed by the Constitution. Naturally it's a good idea, but the Constitution should never be regarded, in a positive manner, as an absolute model for the government to meet.