Libertarian philosophy basically consists of ONE principle. The principle of NON-AGGRESSION. According to libertarian, AGGRESSIVE force cannot be used for any reason whatsoever. Defensive force is permissible to respond to aggression by others. Libertarianism is essentialy a PRINCIPLE that can be accepted or rejected by any philosophy, religion or world-view. It is not itself a complete philosophy and does not mandate any kind of morality or behaviour - other than non-aggression.
Libertarian individuals are free to form voluntary communities based on shared values and regulate these communities as they wish - as long as the communities are truly voluntary.
For example, muslim are free to form an islamic community and regulate it according to Shariah laws. Those who join such communities voluntarily agree to submit to its rules. If they disagree with the rules, they are free to leave or not join in the first place. In such a community, members who engage in pre-marital sex and can be punished according to the rules of the community - since they agreed to these rules. The important thing is that their right to leave voluntarily is not infringed upon.
A perfect example of a libertarian community is the Amish community. They are a very conservative community and strictly enforce their rules among their members. Yet, this enforcement is entirely voluntary. Any member is free to leave. They do not use state corecion AT ALL to enforce their rules. In fact, they try to stay away from the state as much as possible. No, Social Security, No medicare, no public education.