Cannot help feeling, Cannot but, Cannot hold back
Structure
Noun + を禁じ得ない
Verb + の + を禁じ得ない
(A) を禁じ得ない is a formal phrase used when the speaker/writer cannot suppress the rise of certain emotions (sadness, happiness, etc.) or the result of those emotions (like laughter or crying).
It is generally used with a limited number of expressions like: 涙、笑い、同情（の念）、驚き（の念）、怒り、苦しみ、失望、喜び、感動. This expression is uncommon in daily conversation.