第一の方法

public class HomeController : Controller
{
    public ActionResult Index()
    {
        //    (    )
        DateTime dt = Convert.ToDateTime("2016-06-11 23:59:59");

        //TimeZone     ，TimeZone.CurrentTimeZone  ：          。
        TimeZone tz = TimeZone.CurrentTimeZone;

        //           utc      （     utc    8   ）
        TimeSpan ts = tz.GetUtcOffset(dt);

        //             ( :    )    UTC  
        DateTime dtGMT = tz.ToUniversalTime(dt);

        // UTC         
        DateTime localtime = tz.ToLocalTime(dtGMT);

        return View();
    }
}

第2の方法

public class HomeController : Controller
{
    public ActionResult Index()
    {
        //    (    )
        DateTime dt = Convert.ToDateTime("2016-06-11 23:59:59");

        //        utc   （     utc  +8  ，    utc      2016-06-11 15:59:59）
        DateTime utcNow = dt.ToUniversalTime();

        // utc       (  1970-01-01 00:00:00   2016-06-11 15:59:59       )
        double utc = ConvertDateTimeInt(utcNow);

        //           (     utc         ),     2016-06-11 23:59:59
        DateTime dtime = ConvertIntDatetime(utc);
        
        return View();
    }


    /// 

    ///        (     1970-1-1 00:00:00             )
    /// 
    ///     
    ///   
    public double ConvertDateTimeInt(System.DateTime time)
    {
        double intResult = 0;
        System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));
        intResult = (time - startTime).TotalSeconds;
        return intResult;
    }

    /// 

    ///           
    /// 
    ///   
    ///     
    public DateTime ConvertIntDatetime(double utc)
    {
        System.DateTime startTime = TimeZone.CurrentTimeZone.ToLocalTime(new System.DateTime(1970, 1, 1));
        startTime = startTime.AddSeconds(utc);
        startTime = startTime.AddHours(8);//       (    =UTC  +8   )
        return startTime;
    }
}