diff --git a/src/Makefile b/src/Makefile
index cda08995f5538..0f6f9abd5ee95 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -145,6 +145,7 @@ endif
 CLANG_LDFLAGS := $(LLVM_LDFLAGS)
 ifeq ($(OS), Darwin)
 CLANG_LDFLAGS += -Wl,-undefined,dynamic_lookup
+OSLIBS += $(SRCDIR)/mach_dyld_atfork.tbd
 endif
 
 COMMON_LIBPATHS := -L$(build_libdir) -L$(build_shlibdir)
diff --git a/src/mach_dyld_atfork.tbd b/src/mach_dyld_atfork.tbd
new file mode 100644
index 0000000000000..9a5d18099dbcf
--- /dev/null
+++ b/src/mach_dyld_atfork.tbd
@@ -0,0 +1,25 @@
+--- !tapi-tbd
+# copied from XCode's libSystem.tbd (current-version: 1311)
+# to provide weak-linkage info for new symbols on old systems
+tbd-version:     4
+targets:         [ x86_64-macos, x86_64-maccatalyst, arm64-macos, arm64-maccatalyst,
+                   arm64e-macos, arm64e-maccatalyst ]
+uuids:
+  - target:          x86_64-macos
+    value:           AFE6C76A-B47A-35F5-91D0-4E9FC439E90D
+  - target:          x86_64-maccatalyst
+    value:           AFE6C76A-B47A-35F5-91D0-4E9FC439E90D
+  - target:          arm64-macos
+    value:           2EA09BDB-811B-33AA-BB58-4B53AA2DB522
+  - target:          arm64-maccatalyst
+    value:           2EA09BDB-811B-33AA-BB58-4B53AA2DB522
+  - target:          arm64e-macos
+    value:           09AB3723-C26D-3762-93BA-98E9C38B89C1
+  - target:          arm64e-maccatalyst
+    value:           09AB3723-C26D-3762-93BA-98E9C38B89C1
+install-name:    '/usr/lib/libSystem.B.dylib'
+exports:
+  - targets:         [ arm64-macos, arm64e-macos, x86_64-macos, x86_64-maccatalyst,
+                       arm64-maccatalyst, arm64e-maccatalyst ]
+    symbols:         [ __dyld_atfork_parent, __dyld_atfork_prepare ]
+...
diff --git a/src/signals-mach.c b/src/signals-mach.c
index 57dcc969068e8..4ddfad4e10600 100644
--- a/src/signals-mach.c
+++ b/src/signals-mach.c
@@ -31,6 +31,11 @@ extern void *_keymgr_get_and_lock_processwide_ptr(unsigned int key);
 extern int _keymgr_get_and_lock_processwide_ptr_2(unsigned int key, void **result);
 extern int _keymgr_set_lockmode_processwide_ptr(unsigned int key, unsigned int mode);
 
+// private dyld3/dyld4 stuff
+extern void _dyld_atfork_prepare(void) __attribute__((weak_import));
+extern void _dyld_atfork_parent(void) __attribute__((weak_import));
+//extern void _dyld_fork_child(void) __attribute__((weak_import));
+
 static void attach_exception_port(thread_port_t thread, int segv_only);
 
 // low 16 bits are the thread id, the next 8 bits are the original gc_state
@@ -521,6 +526,31 @@ static kern_return_t profiler_segv_handler
 }
 #endif
 
+// WARNING: we are unable to handle sigsegv while the dlsymlock is held
+static int jl_lock_profile_mach(int dlsymlock)
+{
+    jl_lock_profile();
+    // workaround for old keymgr bugs
+    void *unused = NULL;
+    int keymgr_locked = _keymgr_get_and_lock_processwide_ptr_2(KEYMGR_GCC3_DW2_OBJ_LIST, &unused) == 0;
+    // workaround for new dlsym4 bugs (API and bugs introduced in macOS 12.1)
+    if (dlsymlock && _dyld_atfork_prepare != NULL && _dyld_atfork_parent != NULL)
+        _dyld_atfork_prepare();
+    return keymgr_locked;
+}
+
+static void jl_unlock_profile_mach(int dlsymlock, int keymgr_locked)
+{
+    if (dlsymlock && _dyld_atfork_prepare != NULL && _dyld_atfork_parent != NULL) \
+        _dyld_atfork_parent(); \
+    if (keymgr_locked)
+        _keymgr_unlock_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST);
+    jl_unlock_profile();
+}
+
+#define jl_lock_profile()       int keymgr_locked = jl_lock_profile_mach(1)
+#define jl_unlock_profile()     jl_unlock_profile_mach(1, keymgr_locked)
+
 void *mach_profile_listener(void *arg)
 {
     (void)arg;
@@ -537,9 +567,7 @@ void *mach_profile_listener(void *arg)
         HANDLE_MACH_ERROR("mach_msg", ret);
         // sample each thread, round-robin style in reverse order
         // (so that thread zero gets notified last)
-        jl_lock_profile();
-        void *unused = NULL;
-        int keymgr_locked = _keymgr_get_and_lock_processwide_ptr_2(KEYMGR_GCC3_DW2_OBJ_LIST, &unused) == 0;
+        int keymgr_locked = jl_lock_profile_mach(0);
         jl_shuffle_int_array_inplace(profile_round_robin_thread_order, jl_n_threads, &profile_cong_rng_seed);
         for (int idx = jl_n_threads; idx-- > 0; ) {
             // Stop the threads in the random round-robin order.
@@ -550,9 +578,13 @@ void *mach_profile_listener(void *arg)
                 break;
             }
 
+            if (_dyld_atfork_prepare != NULL && _dyld_atfork_parent != NULL)
+                _dyld_atfork_prepare(); // briefly acquire the dlsym lock
             host_thread_state_t state;
             jl_thread_suspend_and_get_state2(i, &state);
             unw_context_t *uc = (unw_context_t*)&state;
+            if (_dyld_atfork_prepare != NULL && _dyld_atfork_parent != NULL)
+                _dyld_atfork_parent(); // quickly release the dlsym lock
 
             if (running) {
 #ifdef LLVMLIBUNWIND
@@ -609,9 +641,7 @@ void *mach_profile_listener(void *arg)
             // We're done! Resume the thread.
             jl_thread_resume(i, 0);
         }
-        if (keymgr_locked)
-            _keymgr_unlock_processwide_ptr(KEYMGR_GCC3_DW2_OBJ_LIST);
-        jl_unlock_profile();
+        jl_unlock_profile_mach(0, keymgr_locked);
         if (running) {
             // Reset the alarm
             kern_return_t ret = clock_alarm(clk, TIME_RELATIVE, timerprof, profile_port);