I am currently holding H1B visa. I'd like to marry a guy who overstayed in america.?

He is not eligible to get an H4 due to his overstay. He will be banned for either 3 or 10 years, depending on how long he has overstayed. Only immediate relatives of US citizens are eligible to gain legal status after overstaying; not even relatives of green card holders have this privilege.

You can mary him. However, as an "overstayer" he is not eligible for a change of status to H4. Also, by going abroad to apply for a visa, he will become inadmissible to USA for 3 or 10 years (depending on a period of overstay).

Well, well, well. This is a good way to lose your visa. If you do anything to aid or abet an illegal alien - e.g. let him in your car, or worse, let him drive it, or allow him in your apartment - then you are subject to the laws prohibiting sheltering, harboring, transporting, etc, of an illegal alien. That's 10 years in prison plus $250,000 fine before you are deported and permanently barred from reentry.

He has to return to his own country, and he will be barred from reentry for 10 years. If you want to marry this guy, he has to return to his country of citizenship, then apply for your immigration to his country. There's no way he's remaining in the US, and no way you two can marry & live together unless you go back to your country & apply for his immigration there, or he goes to his country and applies for your immigration. Of course, if you two are citizens of the same country, just go home, get married, stay there permanently.

Yoyu dont value you status much then ....

send him home to get a visa ... he wont be back ...