Libertarians are fiscally conservative and socially liberal.
They most certainly are not Liberals.
By today's standards, they're not even all that 'socially liberal'. Today's government seeks to actively encourage bad behaviors, both in words (especially in the education system) and in its denial (and mitigation) of their consequences. Libertarians believe that if people were allowed and forced to bear the natural consequences of their own bad actions, there would be no need for the state to explicitly punish them, except in cases where the natural consequences of a person's bad actions would fall upon someone other than the actor.
While I think that the libertarians and Libertarians' platform goes too far in some ways, it's certainly closer to where this country should be than where it is now, and probably closer than the platforms actually held to by most "Republicans".