XCode not finding libgmalloc.dylib when deploying to iPhone

I have an iPhone app that runs great on the simulator, and which ran on my phone too, but now (I think since upgrading to beta 7), when I try to deploy to a device, it can't find the GuardMalloc library (libgmalloc.dylib). Under the simulator it can definitely find it, since the console spits out messages like "GuardMalloc: Allocations will be placed on 16 byte boundaries."

I've spent all night trying to figure out how to add this to the path, or set an environment variable, I even rebuilt a fresh XCode app. I'm stumped, and it's driving me crazy. Any help greatly appreciated. Here's the error I'm getting from the console:

Best,
John

warning: Unable to read symbols from "libgmalloc.B.dylib" (not yet mapped into memory).
Program loaded.
target remote-mobile /tmp/.XcodeGDBRemote-3592-218
Switching to remote protocol
mem 0x1000 0x3fffffff cache
mem 0x40000000 0xffffffff none
mem 0x00000000 0x0fff none
sharedlibrary apply-load-rules all
run
Running…
[Switching to thread 10755]
[Switching to thread 10755]
(gdb) continue
dyld: could not load inserted library: /usr/lib/libgmalloc.dylib