Index: lldb/source/Host/posix/ProcessLauncherPosixFork.cpp
===================================================================
--- lldb/source/Host/posix/ProcessLauncherPosixFork.cpp
+++ lldb/source/Host/posix/ProcessLauncherPosixFork.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/Errno.h"
 
 #include <climits>
+#include <filesystem>
 #include <sys/ptrace.h>
 #include <sys/wait.h>
 #include <unistd.h>
@@ -143,10 +144,30 @@
     // Close everything besides stdin, stdout, and stderr that has no file
     // action to avoid leaking. Only do this when debugging, as elsewhere we
     // actually rely on passing open descriptors to child processes.
-    for (int fd = 3; fd < sysconf(_SC_OPEN_MAX); ++fd)
-      if (!info.GetFileActionForFD(fd) && fd != error_fd)
-        close(fd);
 
+    std::string proc_fd_path = "/proc/self/fd";
+    std::filesystem::path fp(proc_fd_path);
+    if (std::filesystem::is_directory(fp)) {
+      std::vector<int> files_to_close;
+      // Directory iterator doesn't ensure any sequence.
+      for (auto &entry : std::filesystem::directory_iterator(proc_fd_path)) {
+        int fd =
+            std::stoi(entry.path().string().substr(proc_fd_path.size() + 1));
+
+        // Don't close first three entries since they are
+        // stdin/stdout/stderr
+        if ((fd > 2) && !info.GetFileActionForFD(fd) && fd != error_fd)
+          files_to_close.push_back(fd);
+      }
+      for (auto &file_to_close : files_to_close)
+        close(file_to_close);
+    } else {
+      // /proc/self/fd didn't work - trying the slow way instead
+      for (int fd = 3; fd < sysconf(_SC_OPEN_MAX); ++fd)
+        if (!info.GetFileActionForFD(fd) && fd != error_fd) {
+          close(fd);
+        }
+    }
     // Start tracing this child that is about to exec.
     if (ptrace(PT_TRACE_ME, 0, nullptr, 0) == -1)
       ExitWithError(error_fd, "ptrace");