Download link:
https://llvm.org/pre-releases/win-snapshots/ClangFormat-r258122.vsix
Note: There doesn't seem to be a stable plug-in, this plug-in version seems closest to the currently used 3.8 stable version.
Installation instructions:
Everything should be automatically setup correctly. Just make sure Visual Studio is selected in the installer, and after installation open Visual Studio and go to Tools > Options > LLVM/Clang > ClangFormat to make sure Style is set to "file" and Sort Includes is set to "False". Then go to Tools > Extensions And Updates. You might want to disable "Automatically update this extension" displayed on the right.
Note: The Extensions And Updates window also shows the version number and allows for uninstallation of the plug-in.
Usage instructions:
Select the text you want to apply it to and press CTRL+R, followed by CTRL-F, or go to Tools > ClangFormat.