Below I provided a simple step by step instruction on how to compile QT 5.7 with VS2015 assuming you already have VS2015 and Git client installed on your Windows machine.
To get QT 5.7 sources open Git Bash and run the following command (the repository has some submodules, so “recursive” option is required):
git clone --recursive https://github.com/qtproject/qt5.git --branch 5.7
Create a bat file called configureqt.bat with the following content:
set PATH=%PATH%;"C:\Program Files (x86)\Portable\ruby-2.3.0-i386-mingw32\bin";C:\Perl\bin;C:\Python27 D: cd D:\Repos\qt5\ set _ROOT=D:\Repos\qt5 set PATH=%_ROOT%\qtbase\bin;%_ROOT%\gnuwin32\bin;%PATH% set QMAKESPEC=win32-msvc2015 set _ROOT= configure -debug -nomake examples -opensource