Stealing versus Lags

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I need help in how to play Lags who never fold to your steal attempt. I was playing this guy who never folded and basically check raised everytime I bet. For example if you have an A5O, he checks you bet, he raises. Check, check on the turn. He bets the river. Do you fold?
He basically takes this line everytime, no matter what he has. If I raise back on the flop he rebets. I lost 5 out 6 hands to him, when he shows two pairs, with 36O and the such. The only time he lost he showed 27O. I have a hard time folding to someone like this, but more often than not lose money to them, because I can't get a read, as they play 27O, the same as AA. Any help would be appreciated.