Save Objects Instantiated clones in a Text File

I am making A level editor like Halo Forge, I am basing the building off of The Modular Build engine. But It Instantiates objects that you place down as a clone, so when I exit play mode, all of the objects go away. How could I Save The Object and the position/rotation data to a text file via script so that I could load up the scene later and have all of the objects in the same place.

Thanks for any help.