How to make 4v5s more fair

We all hate those games where someone has to go eat or someone wasn't supposed to be playing and got caught. Admittedly we've been those people before too. Well no one likes a 4 v 5 as since league is such a team based game a 4 v 5 is near impossible to win. Well what if Riot gave the people in a 4 v 5 a little buff. I know what your thinking "oh that can easily be abused" or "oh that will make the 4 man team too op". No. I don't mean a buff that would completely overpower the team down 1 man. I mean a small one that's just enough to make up for the missing person. Also so it's not abused why not have it be removed when the person returns. I don't want to personally do the math and that would be Riots job if they ever see this and choose to put it in the game, but i mean come on especially in low elo 4 v 5's are really common and ruins the game for the remaining players. Just wanted to throw some ideas out there.