[CentOS] Opposite of cp -u

I had at one point copied a large number of files between drives and did 
not use the -p and thus the timestamps were all set to the date of the copy.

I did not catch this, and deleted the source.  So I 'lived' with it and 
have since changed many files.

Well, yesterday I found a good backup of many of those files and I want 
to restore them to their proper dates.

cp -p -u is exactly the opposite of what I want.  I want to copy only if 
the source files have an earlier date than the destination files.

The source files are just an old copy on another drive that I found when 
cleaning up things...