Overstayed what, that is the main question. Secondary question is overstayed when.
Ordinarily he will likely need an I-601 due to a 10 year ban for unlawful presence. It can be sought on either IR1 or K-1, the process basically looks the same as normal until the consular interview, where he'll have to go, get denied, then file I-601 with USCIS, then when I-601 is approved reschedule with the consulate, attend another interview and hopefully get the visa approved then. I wouldn't recommend trying to DIY a hardship waiver, tell your friend to get a lawyer, but ultimately, yeah it is possible.
Now there are some cases where it doesn't apply and that's in cases where either you are admitted with no concrete expiration date and there's two groups where that's the case:
1. Admitted for "duration of status", I-94 instead of having an expiration date it'll just say "D/S" (F, J, and M nonimmigrants)
2. Not issued an I-94 to begin with (Canadian tourists, possibly some others?)
Due to a quirk in the regulations the two groups above do not accrue unlawful presence until one of the following happens:
1. USCIS makes a formal finding that they're out of status, which only happens if they apply for something else and get denied.
2. IJ orders removal.
Then it starts to count from the following day. So in case like this someone can overstay an F-1 for years, never apply for anything with USCIS and never end up in removal proceedings, leave, and not get banned.
@Crazy Cat
K-1s are eligible for the I-601.