I'm not aware of such a function, and I can't speak on future availability, but have you (obviously?) tried cooking your own user defined function, eg:
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select getdate() as now,
getutcdate() as now_utc,
current_bigdatetime() as now_big,
dateadd(mi,datediff(mi,getdate(),getutcdate()),current_bigdatetime()) as now_big_utc
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