As stated in my original post, Vin is 0V to +5V and is supplied by a function generator.
I see that Digi-Key have a search filter for rail to rail op amps, so I'll go looking with that. This is probably more elegant than setting up a voltage regulator to to increase the supply voltage on the op amp I already have. I can also rummage through the parts draw and see if there's a rail to rail amp in there somewhere.