diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_mac.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_mac.cpp
@@ -52,16 +52,19 @@
 
 class AtosSymbolizerProcess : public SymbolizerProcess {
  public:
-  explicit AtosSymbolizerProcess(const char *path, pid_t parent_pid)
+  explicit AtosSymbolizerProcess(const char *path)
       : SymbolizerProcess(path, /*use_posix_spawn*/ true) {
-    // Put the string command line argument in the object so that it outlives
-    // the call to GetArgV.
-    internal_snprintf(pid_str_, sizeof(pid_str_), "%d", parent_pid);
+    pid_str_[0] = '\0';
   }
 
  private:
   bool StartSymbolizerSubprocess() override {
     // Configure sandbox before starting atos process.
+
+    // Put the string command line argument in the object so that it outlives
+    // the call to GetArgV.
+    internal_snprintf(pid_str_, sizeof(pid_str_), "%d", internal_getpid());
+
     return SymbolizerProcess::StartSymbolizerSubprocess();
   }
 
@@ -138,7 +141,7 @@
 }
 
 AtosSymbolizer::AtosSymbolizer(const char *path, LowLevelAllocator *allocator)
-    : process_(new(*allocator) AtosSymbolizerProcess(path, getpid())) {}
+    : process_(new (*allocator) AtosSymbolizerProcess(path)) {}
 
 bool AtosSymbolizer::SymbolizePC(uptr addr, SymbolizedStack *stack) {
   if (!process_) return false;
diff --git a/compiler-rt/test/sanitizer_common/TestCases/Darwin/print-stack-trace-in-code-loaded-after-fork.cpp b/compiler-rt/test/sanitizer_common/TestCases/Darwin/print-stack-trace-in-code-loaded-after-fork.cpp
new file mode 100644
--- /dev/null
+++ b/compiler-rt/test/sanitizer_common/TestCases/Darwin/print-stack-trace-in-code-loaded-after-fork.cpp
@@ -0,0 +1,56 @@
+// RUN: %clangxx %s -g -DSHARED_LIB -shared -o %t_shared_lib.dylib
+// RUN: %clangxx %s -g -USHARED_LIB -o %t_loader
+// RUN: %env_tool_opts=verbosity=3 %run %t_loader %t_shared_lib.dylib > %t_loader_output.txt 2>&1
+// RUN: FileCheck -input-file=%t_loader_output.txt %s
+// RUN: FileCheck -check-prefix=CHECK-STACKTRACE -input-file=%t_loader_output.txt %s
+
+#include <stdio.h>
+
+#ifdef SHARED_LIB
+#include <sanitizer/common_interface_defs.h>
+
+extern "C" void PrintStack() {
+  fprintf(stderr, "Calling __sanitizer_print_stack_trace\n");
+  // CHECK-STACKTRACE: #0{{( *0x.* *in *)?}}  __sanitizer_print_stack_trace
+  // CHECK-STACKTRACE: #1{{( *0x.* *in *)?}} PrintStack {{.*}}print-stack-trace-in-code-loaded-after-fork.cpp:[[@LINE+1]]
+  __sanitizer_print_stack_trace();
+}
+#else
+#include <assert.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+typedef void (*PrintStackFnPtrTy)(void);
+
+int main(int argc, char **argv) {
+  assert(argc == 2);
+  pid_t pid = fork();
+  if (pid != 0) {
+    // Parent
+    pid_t parent_pid = getpid();
+    fprintf(stderr, "parent: %d\n", parent_pid);
+    int status = 0;
+    pid_t child = waitpid(pid, &status, /*options=*/0);
+    assert(pid == child);
+    bool clean_exit = WIFEXITED(status) && WEXITSTATUS(status) == 0;
+    return !clean_exit;
+  }
+  // Child.
+  pid = getpid();
+  // CHECK: child: [[CHILD_PID:[0-9]+]]
+  fprintf(stderr, "child: %d\n", pid);
+  const char *library_to_load = argv[1];
+  void *handle = dlopen(library_to_load, RTLD_NOW | RTLD_LOCAL);
+  assert(handle);
+  PrintStackFnPtrTy PrintStackFnPtr = (PrintStackFnPtrTy)dlsym(handle, "PrintStack");
+  assert(PrintStackFnPtr);
+  // Check that the symbolizer is told examine the child process.
+  // CHECK: Launching Symbolizer process: {{.+}}atos -p [[CHILD_PID]]
+  // CHECK-STACKTRACE: #2{{( *0x.* *in *)?}} main {{.*}}print-stack-trace-in-code-loaded-after-fork.cpp:[[@LINE+1]]
+  PrintStackFnPtr();
+  return 0;
+}
+
+#endif