Does Libertarianism necessarily mean anarch-capitalism?

Here in Brazil libertarianism means anarch-capitalism. However, "liberals" are considered defensors of a free market economy and social liberty. But in the USA, it means more of a "social liberty for minorities", therefore more of a left wing concept. So, if libertarianism necessarily means anarch-capitalism, what a "brazilian liberal" (libertarians that think that a form of governament is necessary) would be called in the US?