Roderick Long argues that classical eudaimonism provides a key to reconciling the egoistic and natural-rights justifications for a voluntary society, since eudaimonism holds that justice is part of human flourishing. Long adduces Socrates as the originator, and Plato, Aristotle, and the Stoics as early developers, of the eudaimonist tradition; he also notes that eudaimonist views on the content of justice are quite foreign to the theories of justice inherent in individualist anarchism. It's interesting to me that he left Epicurus off the list of eudaimonist thinkers, because certain Epicurean positions seem to present an approach to justice that is much closer to individualist anarchism. Consider these passages from the Principal Doctrines:
Natural justice is a pledge to be useful by neither harming one another nor being harmed. (31)
Justice is not a thing in itself, but is a contract to neither harm one another nor be harmed that arises at some place or another in people's dealings with each other. (33)
Generally speaking, justice is the same for everyone, since it is something useful in people's relationships with one another.... (36)
... If someone passes a law and it does not turn out to be in accord with what is useful in mutual associations, then it no longer possesses the nature of justice.... (37)
... If circumstances change and the same things which had been just turn out to be no longer useful, then those things were just as long as they were useful for people's relationships with one another.... (38)
For Epicurus, justice arises from a pledge of non-aggression, a reciprocal agreement to not harm others and not be harmed by them. Such a contract benefits both parties and therefore is of great utility for people's social relationships. But if someone passes a law that that is not useful in this way, then it is unjust. Sounds a lot like a libertarian approach to social philosophy.
All those Aristotelian libertarians out there might want to investigate Epicurus more deeply.