Not many one-syllable English words end in the letters -lm. Sometimes the l in them is pronounced; sometimes it isn’t.
Here’s a list of the most common -lm words, together with the pronunciation in the phonetic notation given at Answers.com. Many Americans pronounce all of these words with an l.
These pronunciations all agree with those given in the OED.
Additionally, the OED acknowledges U.S. pronunciations with the sound of l for palm, psalm, and qualm.
Merriam-Webster uses the symbol ] to indicate a sound that “facilitates the placement of variant pronunciation.” For example, ￼ä]mz. This symbol, which seems to indicate an “almost l,” is used for the first pronunciation given for alms, balm, calm, embalm, palm, psalm, and qualm. The pronunciation with a full l sound is given as an alternate: also ]lm.