Could not copy "C:\Whatever\LibSassHost.Native\msvcp120.dll" to "bin\LisSassHost.Native\msvcp120.dll". Exceeded retry count 10. Failed.

When I got this error upon attempting to compile in Visual Studio 2015, I learned to deal with it by turning IIS off when compiling. If there is a way to change the .dll from "Copy Always" to "Copy Newer" that helps in situations like this.