I've recently blogged about adding TLS support to Emacs 24.5 on Windows and improving git performance on Windows by installing an alternative git command line client. The reason I ended up investigating how to add SSL and TLS support to Emacs is that when I originally upgraded from the official git Windows client to the Git for Windows build, I ended up with non-working TLS support in Emacs.
The TLS issues only occur if you tell the git installer to add git and all supporting Unix utilities to the path, which is not the default setting for a git installation on Windows.
However if you do install git with this setting, Emacs ends up finding the openssl libraries on the path. This works fine with the older versions packaged with the installer from git-scm.com but results in TLS issues with SSL/TLS connections failing with the newer binaries shipped with Git for Windows. I didn't dig deeper into why I was seeing the issue as I was in a hurry to get Emacs working again, so I looked for the quickest way to resolve it.
tl;dr - if you're running into TLS issues with Emacs on Windows and just installed Git for Windows, follow the instructions in Adding TLS Support to Emacs 24.5 on Windows to get SSL/TLS connection from inside Emacs working again.