Answer by SherylHohman for How to add more commands to Git Bash?

to add rsync

You can download the rsync file directly from mysys. Just search the page for rsync and choose the one with the latest date / latest version number.
Unpack this file (e.g. rsync-3.1.3-1-x86_64.pkg.tar.xz) via

tar -xf rsync-3.1.3-1-x86_64.pkg.tar.xz

Then copy rsync at ./usr/bin/rsync.exeand paste it into the /usr/bin folder of your Git installation.
On my machine, that is C:/Program Files/Git/usr/bin/

You can see the location of your Git installation via

where git

Here is a GitHub gist by "hisplan" (Jaeyoung Chun) that has instructions along with a link to the 3.1.3-1 version of rsync: add-rsync-to-git-bash.

Note: I could not unpack the rsync-3.1.3-1-x86_64.pkg.tar.xz file directly into the Git folder, because permissions did not allow it. And Git Bash does not have sudo.
But I could unpack it directly into my Downloads folder no problem.
It's just as well, because you only need the rsync.exe file anyway.