Harvard's Jeff Miron is a traditionally trained, neoclassical economist with surprisingly strong libertarian views. Here is his utilitarian case against antitrust enforcement. (He is best known among libertarians for his opposition to drug prohibition.)
Miron was mentioned previously on this blog for offering an undergraduate economics course on libertarianism without a single reading from Rothbard, Hazlitt, Mises, Hayek, Jefferson, Spooner, Sumner, or Boetie.