No, there is nothing like C-style /* */ comments in makefiles. As somebody else suggested, you can make a multi-line comment by using line continuations. For example:
# This is the first line of a comment \
and this is still part of the comment \
as is this, since I keep ending each line \
with a backslash character
However, I imagine that you are probably looking to temporarily comment out a chunk of your makefile for debugging reasons, and adding a backslash on every line is not really practical. If you are using GNU make, I suggest you use the ifeq directive with a deliberately false expression. For example:
ifeq ("x","y")
# here's all your 'commented' makefile content...
endif
Hope that helps.