Tough makefile question

At my company, we build some stuff using a makefile. While the makefile script is running, a developer may check in a newer version of a source file. The problem is, when we next run the make command, the target file isn't rebuilt, because the date of the target is after the dependency.

Any ideas to get this to work without rebuilding everything every time?

After the build is complete, set the timestamp of all files used and generated to the exact time the build was started.

Then when you do a cvs update or whatever newer files will be shown as newer.