Doable using Hive date udf's (DATEDIFF, FROM_UNIXTIME, UNIX_TIMESTAMP, DATE_ADD): https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF#LanguageManualUDF-DateFunctions
Assuming your source table definition is: DateSource(col1 string, col2 string, myDate string)
The query would be:
SELECT col1, col2, myDate, DATE_ADD(myDate,daysDiff) as adjustedDate
FROM DateSource
JOIN
(
SELECT DATEDIFF(FROM_UNIXTIME(UNIX_TIMESTAMP(),"yyyy-MM-dd"),maxDate) as daysDiff
FROM
(
SELECT max(myDate) as maxDate FROM DateSource
) maxDate
) diffDate;