Index: lldb/tools/debugserver/source/DNB.h
===================================================================
--- lldb/tools/debugserver/source/DNB.h
+++ lldb/tools/debugserver/source/DNB.h
@@ -235,4 +235,7 @@
 bool DNBGetOSVersionNumbers(uint64_t *major, uint64_t *minor, uint64_t *patch);
 /// \return the iOSSupportVersion of the host OS.
 std::string DNBGetMacCatalystVersionString();
+
+nub_bool_t DNBStopSTDIOThread(nub_process_t pid);
+
 #endif
Index: lldb/tools/debugserver/source/DNB.cpp
===================================================================
--- lldb/tools/debugserver/source/DNB.cpp
+++ lldb/tools/debugserver/source/DNB.cpp
@@ -1732,3 +1732,12 @@
   }
   return false;
 }
+
+nub_bool_t DNBStopSTDIOThread(nub_process_t pid) {
+  MachProcessSP procSP;
+  if (GetProcessSP(pid, procSP)) {
+    procSP->StopSTDIOThread();
+    return true;
+  }
+  return false;
+}
Index: lldb/tools/debugserver/source/MacOSX/MachProcess.h
===================================================================
--- lldb/tools/debugserver/source/MacOSX/MachProcess.h
+++ lldb/tools/debugserver/source/MacOSX/MachProcess.h
@@ -187,6 +187,7 @@
 
   // Exception thread functions
   bool StartSTDIOThread();
+  void StopSTDIOThread();
   static void *STDIOThread(void *arg);
   void ExceptionMessageReceived(const MachException::Message &exceptionMessage);
   task_t ExceptionMessageBundleComplete();
@@ -299,6 +300,9 @@
   int GetStdinFileDescriptor() const { return m_child_stdin; }
   int GetStdoutFileDescriptor() const { return m_child_stdout; }
   int GetStderrFileDescriptor() const { return m_child_stderr; }
+  int GetStdoutThreadInterruptFileDescriptor() const {
+    return m_stdio_thread_interrupt[0];
+  }
   void AppendSTDOUT(char *s, size_t len);
   size_t GetAvailableSTDOUT(char *buf, size_t buf_size);
   size_t GetAvailableSTDERR(char *buf, size_t buf_size);
@@ -368,6 +372,9 @@
   uint32_t m_stop_count; // A count of many times have we stopped
   pthread_t m_stdio_thread;   // Thread ID for the thread that watches for child
                               // process stdio
+  int m_stdio_thread_interrupt[2]; // File descriptor pair to notify STDIO
+                                   // thread that it should stop waiting for
+                                   // input and finish.
   PThreadMutex m_stdio_mutex; // Multithreaded protection for stdio
   std::string m_stdout_data;
 
Index: lldb/tools/debugserver/source/MacOSX/MachProcess.mm
===================================================================
--- lldb/tools/debugserver/source/MacOSX/MachProcess.mm
+++ lldb/tools/debugserver/source/MacOSX/MachProcess.mm
@@ -1316,15 +1316,29 @@
   }
   m_activities.Clear();
   StopProfileThread();
+  StopSTDIOThread();
 }
 
 bool MachProcess::StartSTDIOThread() {
   DNBLogThreadedIf(LOG_PROCESS, "MachProcess::%s ( )", __FUNCTION__);
+  if (pipe(m_stdio_thread_interrupt) == -1) {
+    return false;
+  }
   // Create the thread that watches for the child STDIO
   return ::pthread_create(&m_stdio_thread, NULL, MachProcess::STDIOThread,
                           this) == 0;
 }
 
+void MachProcess::StopSTDIOThread() {
+  if (m_stdio_thread) {
+    ::write(m_stdio_thread_interrupt[1], "", 1);
+    pthread_join(m_stdio_thread, nullptr);
+    m_stdio_thread = 0;
+    close(m_stdio_thread_interrupt[0]);
+    close(m_stdio_thread_interrupt[1]);
+  }
+}
+
 void MachProcess::SetEnableAsyncProfiling(bool enable, uint64_t interval_usec,
                                           DNBProfileDataScanType scan_type) {
   m_profile_enabled = enable;
@@ -2388,6 +2402,8 @@
   DNBError err;
   int stdout_fd = proc->GetStdoutFileDescriptor();
   int stderr_fd = proc->GetStderrFileDescriptor();
+  int interrupt_fd = proc->GetStdoutThreadInterruptFileDescriptor();
+
   if (stdout_fd == stderr_fd)
     stderr_fd = -1;
 
@@ -2400,7 +2416,10 @@
       FD_SET(stdout_fd, &read_fds);
     if (stderr_fd >= 0)
       FD_SET(stderr_fd, &read_fds);
-    int nfds = std::max<int>(stdout_fd, stderr_fd) + 1;
+
+    FD_SET(interrupt_fd, &read_fds);
+
+    int nfds = std::max<int>({stdout_fd, stderr_fd, interrupt_fd}) + 1;
 
     int num_set_fds = select(nfds, &read_fds, NULL, NULL, NULL);
     DNBLogThreadedIf(LOG_PROCESS,
@@ -2478,6 +2497,9 @@
 
         } while (bytes_read > 0);
       }
+      if (FD_ISSET(interrupt_fd, &read_fds)) {
+        break;
+      }
     }
   }
   DNBLogThreadedIf(LOG_PROCESS, "MachProcess::%s (%p): thread exiting...",
Index: lldb/tools/debugserver/source/debugserver.cpp
===================================================================
--- lldb/tools/debugserver/source/debugserver.cpp
+++ lldb/tools/debugserver/source/debugserver.cpp
@@ -533,6 +533,13 @@
                      ctx.EventsAsString(set_events, set_events_str));
 
     if (set_events) {
+
+      if (set_events & RNBContext::event_proc_thread_exiting &&
+          remote->Context().HasValidProcessID()) {
+        // Make sure we have all the STDIO read from the process before
+        // flushing.
+        DNBStopSTDIOThread(remote->Context().ProcessID());
+      }
       if ((set_events & RNBContext::event_proc_thread_exiting) ||
           (set_events & RNBContext::event_proc_stdio_available)) {
         remote->FlushSTDIO();