Hard Edges

So I am making a town model in google sketchup, and as you may imagine, it is littered with hard edges. In Unity these edges are covered in white dots, especially the further I get from them, it becomes a horrible, flashing, white outline.

I don't fully understand how to solve this. I have read that the trick is to not calculate normals, however when I do this the entire mesh turns black (because it is using a diffuse shader which requires normals). I tried using a self-illumination shader but my game has a (rather crude) day scale therefore when it becomes night time the buildings are all glowing. So community, what do you think is my best bet for solving this problem? Is there a shader that does not require normals but can calculate light? Or a self-illumination shader that is based on the light around? Or perhaps an entirely different approach to softening the hard edges? Thank you all so much in advanced!

P.S. I would like to avoid having to go into sketchup and create more edges in order to smooth them due to the already absurdly high amount of polys the sketchup models bring with them when exported! Thanks again!