Compiling project with VS2017 (v141) toolchain

Simple question, is there any way to specify the desired toolchain to be used for compilation? Even though I use VS2017 as my IDE right now, and solutions are generated for that correctly, when compiling it is still using the v140 toolchain as can be easily detected (_MSC_VER == 1900).

How do I enforce usage of VS2017? I’d like to use features that are not available in VS2015.

Bump. I am now using UE 4.18 yet the compiler toolchain used is still VS2015 - v140

For Projects Edit → Editor Preferences → General → Source Code → Choose 2017

For Engine Source run “GenerateProjectFiles.bat -2017”