diff --git a/src/syscall/exec_libc2.go b/src/syscall/exec_libc2.go
index 9eb61a5..f4be784 100644
--- a/src/syscall/exec_libc2.go
+++ b/src/syscall/exec_libc2.go
@@ -78,7 +78,7 @@
 	// About to call fork.
 	// No more allocation or calls of non-assembly functions.
 	runtime_BeforeFork()
-	r1, _, err1 = rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
+	r1, _, err1 = rawSyscall(forkTrampoline, 0, 0, 0)
 	if err1 != 0 {
 		runtime_AfterFork()
 		return 0, err1
@@ -276,6 +276,6 @@
 	// send error code on pipe
 	rawSyscall(abi.FuncPCABI0(libc_write_trampoline), uintptr(pipe), uintptr(unsafe.Pointer(&err1)), unsafe.Sizeof(err1))
 	for {
-		rawSyscall(abi.FuncPCABI0(libc_exit_trampoline), 253, 0, 0)
+		rawSyscall(exitTrampoline, 253, 0, 0)
 	}
 }
diff --git a/src/syscall/syscall_darwin.go b/src/syscall/syscall_darwin.go
index 663bd98..b0d89d0 100644
--- a/src/syscall/syscall_darwin.go
+++ b/src/syscall/syscall_darwin.go
@@ -22,7 +22,34 @@
 func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
 func RawSyscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
 
-var dupTrampoline = abi.FuncPCABI0(libc_dup2_trampoline)
+// These are called from exec_libc2.go in the child of fork.
+// The names differ between macOS and OpenBSD, so we need
+// to declare the specific ones used here to keep the exec_libc2.go
+// code portable.
+//
+// We use __fork and __exit, not fork and exit, to avoid the libc atfork
+// and atexit handlers. The atfork handlers have caused fork child
+// hangs in the past (see #33565, #56784). The atexit handlers have
+// not, but the non-libc ports all invoke the system call, so doing
+// the same here makes sense. In general we wouldn't expect
+// atexit handlers to work terribly well in a fork child anyway.
+// (Also, perhaps the atfork handlers clear the atexit handlers,
+// in which case we definitely need to avoid calling the libc exit
+// if we bypass the libc fork.)
+//
+// Other calls that are made in the child after the fork are
+// ptrace, setsid, setpgid, getpid, ioctl, chroot, setgroups,
+// setgid, setuid, chdir, dup2, fcntl, close, execve, and write.
+// Those are all simple kernel wrappers that should be safe
+// to be called directly. The fcntl and ioctl functions do run
+// some code around the kernel call, but they don't call any
+// other functions, so for now we keep using them instead of
+// calling the lower-level __fcntl and __ioctl functions.
+var (
+	dupTrampoline  = abi.FuncPCABI0(libc_dup2_trampoline)
+	exitTrampoline = abi.FuncPCABI0(libc___exit_trampoline)
+	forkTrampoline = abi.FuncPCABI0(libc___fork_trampoline)
+)
 
 type SockaddrDatalink struct {
 	Len    uint8
@@ -209,11 +236,12 @@
 //sys	writev(fd int, iovecs []Iovec) (cnt uintptr, err error)
 //sys   mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
 //sys   munmap(addr uintptr, length uintptr) (err error)
-//sysnb fork() (pid int, err error)
+//sysnb __fork() (pid int, err error)
 //sysnb ioctl(fd int, req int, arg int) (err error)
 //sysnb ioctlPtr(fd int, req uint, arg unsafe.Pointer) (err error) = SYS_ioctl
 //sysnb execve(path *byte, argv **byte, envp **byte) (err error)
 //sysnb exit(res int) (err error)
+//sysnb __exit(res int) (err error)
 //sys	sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error)
 //sys	fcntlPtr(fd int, cmd int, arg unsafe.Pointer) (val int, err error) = SYS_fcntl
 //sys   unlinkat(fd int, path string, flags int) (err error)
diff --git a/src/syscall/syscall_openbsd_libc.go b/src/syscall/syscall_openbsd_libc.go
index 516d029..6358a9a 100644
--- a/src/syscall/syscall_openbsd_libc.go
+++ b/src/syscall/syscall_openbsd_libc.go
@@ -10,7 +10,11 @@
 	"internal/abi"
 )
 
-var dupTrampoline = abi.FuncPCABI0(libc_dup3_trampoline)
+var (
+	dupTrampoline  = abi.FuncPCABI0(libc_dup3_trampoline)
+	exitTrampoline = abi.FuncPCABI0(libc_exit_trampoline)
+	forkTrampoline = abi.FuncPCABI0(libc_fork_trampoline)
+)
 
 func init() {
 	execveOpenBSD = execve
diff --git a/src/syscall/zsyscall_darwin_amd64.go b/src/syscall/zsyscall_darwin_amd64.go
index ee78a57..fcb038e 100644
--- a/src/syscall/zsyscall_darwin_amd64.go
+++ b/src/syscall/zsyscall_darwin_amd64.go
@@ -1714,8 +1714,8 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func fork() (pid int, err error) {
-	r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
+func __fork() (pid int, err error) {
+	r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
 	pid = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
@@ -1723,9 +1723,9 @@
 	return
 }
 
-func libc_fork_trampoline()
+func libc___fork_trampoline()
 
-//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
+//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
@@ -1781,6 +1781,20 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func __exit(res int) (err error) {
+	_, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc___exit_trampoline()
+
+//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
 	var _p0 unsafe.Pointer
 	if len(mib) > 0 {
diff --git a/src/syscall/zsyscall_darwin_amd64.s b/src/syscall/zsyscall_darwin_amd64.s
index 563083d..1815703 100644
--- a/src/syscall/zsyscall_darwin_amd64.s
+++ b/src/syscall/zsyscall_darwin_amd64.s
@@ -219,14 +219,16 @@
 	JMP	libc_mmap(SB)
 TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_munmap(SB)
-TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_fork(SB)
+TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
+	JMP	libc___fork(SB)
 TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_ioctl(SB)
 TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_execve(SB)
 TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_exit(SB)
+TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
+	JMP	libc___exit(SB)
 TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_sysctl(SB)
 TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0
diff --git a/src/syscall/zsyscall_darwin_arm64.go b/src/syscall/zsyscall_darwin_arm64.go
index ac1eccf..a4bdcee 100644
--- a/src/syscall/zsyscall_darwin_arm64.go
+++ b/src/syscall/zsyscall_darwin_arm64.go
@@ -1714,8 +1714,8 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
-func fork() (pid int, err error) {
-	r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc_fork_trampoline), 0, 0, 0)
+func __fork() (pid int, err error) {
+	r0, _, e1 := rawSyscall(abi.FuncPCABI0(libc___fork_trampoline), 0, 0, 0)
 	pid = int(r0)
 	if e1 != 0 {
 		err = errnoErr(e1)
@@ -1723,9 +1723,9 @@
 	return
 }
 
-func libc_fork_trampoline()
+func libc___fork_trampoline()
 
-//go:cgo_import_dynamic libc_fork fork "/usr/lib/libSystem.B.dylib"
+//go:cgo_import_dynamic libc___fork __fork "/usr/lib/libSystem.B.dylib"
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
@@ -1781,6 +1781,20 @@
 
 // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
 
+func __exit(res int) (err error) {
+	_, _, e1 := rawSyscall(abi.FuncPCABI0(libc___exit_trampoline), uintptr(res), 0, 0)
+	if e1 != 0 {
+		err = errnoErr(e1)
+	}
+	return
+}
+
+func libc___exit_trampoline()
+
+//go:cgo_import_dynamic libc___exit __exit "/usr/lib/libSystem.B.dylib"
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
 func sysctl(mib []_C_int, old *byte, oldlen *uintptr, new *byte, newlen uintptr) (err error) {
 	var _p0 unsafe.Pointer
 	if len(mib) > 0 {
diff --git a/src/syscall/zsyscall_darwin_arm64.s b/src/syscall/zsyscall_darwin_arm64.s
index 0567a42..1666cf9 100644
--- a/src/syscall/zsyscall_darwin_arm64.s
+++ b/src/syscall/zsyscall_darwin_arm64.s
@@ -219,14 +219,16 @@
 	JMP	libc_mmap(SB)
 TEXT ·libc_munmap_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_munmap(SB)
-TEXT ·libc_fork_trampoline(SB),NOSPLIT,$0-0
-	JMP	libc_fork(SB)
+TEXT ·libc___fork_trampoline(SB),NOSPLIT,$0-0
+	JMP	libc___fork(SB)
 TEXT ·libc_ioctl_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_ioctl(SB)
 TEXT ·libc_execve_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_execve(SB)
 TEXT ·libc_exit_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_exit(SB)
+TEXT ·libc___exit_trampoline(SB),NOSPLIT,$0-0
+	JMP	libc___exit(SB)
 TEXT ·libc_sysctl_trampoline(SB),NOSPLIT,$0-0
 	JMP	libc_sysctl(SB)
 TEXT ·libc_unlinkat_trampoline(SB),NOSPLIT,$0-0