Located in the game directory. Labelled as :MetroLLbenchmark
Also in Steam : right click on the game and select launch benchmark utility.
Yeah, that's where it is suppose to be. But I don't have it in the Steam/Steamapps/Common/Metro Last Light folder:
And it deosn't show up in the right-click menu in Steam either:
I even re-downloaded the game and verified game files.