7-Zip has the ability to split a file, then combine it again. I'm sure most other compression software such as Winzip probably have this feature as well. I have never tried splitting an 8GB file before so I don't know if 7-Zip can handle a file that large but you could certainly try it.
I'm sure there is overhead so if the file is truly 8GB, splitting it in2 will probably result in a file larger than 4GB. You may need to split it into 3 parts.
7-Zip