Ron Paul is as close as they come, I suppose. I'm registered Republican, myself. But I wouldn't say too many Republicans legislate like little-l libertarians.
Sadly, the overwhelming majority of congress is socialist, varying only in the degree to which they embrace redistributionist and authoritarian policy.
The most notable exception being Congressman Ron Paul (who curiously enough was a libertarian candidate for president of the United States)
Well, there's Ron Paul..
Oh, whoops.. He's a Republican.