unity3d 4.6.1 crash. System out of memory when building.

My unity3d crashed in the building process, maybe it consume a 32-bit program can access the highest memory.

This may be related to the resource folder there are too many prefab, when I try to delete the part of the prefab file after unity3d the compiler can finish the work.

My resources folder size 650MB ,Contains 4750 files and 354 folders,including 1345 prefab file.

Now what should I do?