LM317 to step voltage up
An LM317 is defined by many parameters, not just the equation you provide. All of the required operating conditions must be satisfied, and one of the those is the "minimum dropout voltage". This is the minimum difference between the input and output voltage, where the input voltage must be greater than the output voltage. The datasheet for your specific LM317 will provide that number.

Edit: For the Texas Instrument's version of the LM317, the important parameter is in section 6.3 of the datasheet.