Downloaded the icu libraries from http://download.qt.io/development_releases/prebuilt/icu/prebuilt/msvc2013/icu_53_1_msvc_2013_64_devel.7z. Configured Qt 5.6 build with -icu option. Built Qt 5.6 debug version from Qt 5.6 source code. Ran the windeployqt on a Qt application file; in my case, I built QtWebEngineWidgets demo browser and then ran “windeployqt demobrowser.exe”. The MSVCR120.dll and MSVCP120.dll, the dependencies of the icu libraries, were not included. When launching the demo browser on a Windows system that doesn’t have msvc 2013 installed, the demo browser failed to start with an error due to the missing msvc libraries.