It used to be that you could extract the diff for change with a command
svn diff -c 323998 http://llvm.org/svn/llvm-project/cfe/trunk
I now get:
svn: E175013: Access to '/svn/llvm-project/!svn/vcc/default' forbidden
I uses this to extract upstream patches for release version of llvm
products to add to the packages in FreeBSD. If there's another prefered
option please let me know and I'll use that.