--- qemu-2.3.0/linux-user/syscall.c.orig	2014-12-09 14:45:43.000000000 +0000
+++ qemu-2.3.0/linux-user/syscall.c	2015-03-27 06:33:00.736000000 +0000
@@ -227,7 +227,21 @@
 _syscall3(int,sys_rt_sigqueueinfo,int,pid,int,sig,siginfo_t *,uinfo)
 _syscall3(int,sys_syslog,int,type,char*,bufp,int,len)
 #if defined(TARGET_NR_tgkill) && defined(__NR_tgkill)
-_syscall3(int,sys_tgkill,int,tgid,int,pid,int,sig)
+
+extern unsigned int afl_forksrv_pid;
+
+static int sys_tgkill(int tgid, int pid, int sig) {
+
+  /* Workaround for -lpthread to make abort() work properly, without
+     killing the forkserver due to a prematurely cached PID. */
+
+  if (afl_forksrv_pid && afl_forksrv_pid == pid && sig == SIGABRT)
+    pid = tgid = getpid();
+
+  return syscall(__NR_sys_tgkill, pid, tgid, sig);
+
+}
+
 #endif
 #if defined(TARGET_NR_tkill) && defined(__NR_tkill)
 _syscall2(int,sys_tkill,int,tid,int,sig)