diff --git a/src/runtime.cc b/src/runtime.cc
index d8beae8..e1c3099 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -17,6 +17,7 @@
 #include "runtime.h"
 
 #include <signal.h>
+#include <sys/syscall.h>
 
 #include <cstdio>
 #include <cstdlib>
@@ -168,6 +169,7 @@
     LOG(INTERNAL_FATAL) << "Unexpectedly returned from abort hook!";
   }
 
+#if defined(__BIONIC__)
   // TODO: finish merging patches to fix abort(3) in bionic, then lose this!
   // Bionic doesn't implement POSIX semantics for abort(3) in a multi-threaded
   // process, so if we call abort(3) on a device, all threads in the process
@@ -178,7 +180,17 @@
   // We can also trivially tell the difference between a crash and
   // a deliberate abort by looking at the fault address.
   *reinterpret_cast<char*>(0xdeadd00d) = 38;
-  abort();
+#elif defined(__APPLE__)
+  // TODO: check that this actually gives good stack traces on the Mac!
+  pthread_kill(pthread_self(), SIGABRT);
+#else
+  // TODO: we ought to be able to use pthread_kill(3) here (or abort(3),
+  // which POSIX defines in terms of raise(3), which POSIX defines in terms
+  // of pthread_kill(3)). On Linux, though, libcorkscrew can't unwind through
+  // libpthread, which means the stacks we dump would be useless. Calling
+  // tgkill(2) directly avoids that.
+  syscall(__NR_tgkill, getpid(), GetTid(), SIGABRT);
+#endif
   // notreached
 }
 
diff --git a/src/runtime_linux.cc b/src/runtime_linux.cc
index e2c806d..3e39fa2 100644
--- a/src/runtime_linux.cc
+++ b/src/runtime_linux.cc
@@ -258,6 +258,9 @@
 };
 
 static void HandleUnexpectedSignal(int signal_number, siginfo_t* info, void* raw_context) {
+  static Mutex unexpected_signal_lock("unexpected signal lock");
+  MutexLock mu(unexpected_signal_lock);
+
   bool has_address = (signal_number == SIGILL || signal_number == SIGBUS ||
                       signal_number == SIGFPE || signal_number == SIGSEGV);
 
@@ -283,6 +286,15 @@
     while (true) {
     }
   }
+
+  // Remove our signal handler for this signal...
+  struct sigaction action;
+  memset(&action, 0, sizeof(action));
+  sigemptyset(&action.sa_mask);
+  action.sa_handler = SIG_DFL;
+  sigaction(signal_number, &action, NULL);
+  // ...and re-raise so we die with the appropriate status.
+  kill(getpid(), signal_number);
 }
 
 void Runtime::InitPlatformSignalHandlers() {
@@ -291,11 +303,12 @@
   memset(&action, 0, sizeof(action));
   sigemptyset(&action.sa_mask);
   action.sa_sigaction = HandleUnexpectedSignal;
-  action.sa_flags = SA_RESTART;
   // Use the three-argument sa_sigaction handler.
   action.sa_flags |= SA_SIGINFO;
-  // Remove ourselves as signal handler for this signal, in case of recursion.
-  action.sa_flags |= SA_RESETHAND;
+#if !defined(__APPLE__)
+  // Use the alternate signal stack so we can catch stack overflows.
+  action.sa_flags |= SA_ONSTACK;
+#endif
 
   int rc = 0;
   rc += sigaction(SIGILL, &action, NULL);