diff --git a/lldb/include/lldb/Target/Process.h b/lldb/include/lldb/Target/Process.h
--- a/lldb/include/lldb/Target/Process.h
+++ b/lldb/include/lldb/Target/Process.h
@@ -2075,6 +2075,10 @@
 
   void UpdateThreadListIfNeeded();
 
+  /// Method to be invoked to signal that the underlying process has exec'ed
+  /// and some clean up should be done to prepare for the new process state.
+  void ProcessDidExec();
+
   ThreadList &GetThreadList() { return m_thread_list; }
 
   // When ExtendedBacktraces are requested, the HistoryThreads that are created
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -2611,8 +2611,7 @@
     Log *log(ProcessGDBRemoteLog::GetLogIfAllCategoriesSet(GDBR_LOG_PROCESS));
     LLDB_LOGF(log, "ProcessGDBRemote::SetLastStopPacket () - detected exec");
 
-    m_thread_list_real.Clear();
-    m_thread_list.Clear();
+    ProcessDidExec();
     BuildDynamicRegisterInfo(true);
     m_gdb_comm.ResetDiscoverableSettings(did_exec);
   }
diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp
--- a/lldb/source/Target/Process.cpp
+++ b/lldb/source/Target/Process.cpp
@@ -1248,6 +1248,12 @@
   return false;
 }
 
+void Process::ProcessDidExec() {
+  m_thread_list_real.Clear();
+  m_thread_list.Clear();
+  m_thread_plans.Clear();
+}
+
 void Process::UpdateThreadListIfNeeded() {
   const uint32_t stop_id = GetStopID();
   if (m_thread_list.GetSize(false) == 0 ||
diff --git a/lldb/test/API/functionalities/exec/TestExec.py b/lldb/test/API/functionalities/exec/TestExec.py
--- a/lldb/test/API/functionalities/exec/TestExec.py
+++ b/lldb/test/API/functionalities/exec/TestExec.py
@@ -24,7 +24,8 @@
     @skipIfAsan # rdar://problem/43756823
     @skipIfWindows
     def test_hitting_exec (self):
-        self.do_test(False)
+        self.do_test(False, False)
+        self.do_test(False, True)
 
     @expectedFailureAll(archs=['i386'],
                         oslist=no_match(["freebsd"]),
@@ -34,9 +35,10 @@
     @skipIfAsan # rdar://problem/43756823
     @skipIfWindows
     def test_skipping_exec (self):
-        self.do_test(True)
+        self.do_test(True, False)
+        self.do_test(True, True)
 
-    def do_test(self, skip_exec):
+    def do_test(self, skip_exec, should_attach):
         self.build()
         exe = self.getBuildArtifact("a.out")
         secondprog = self.getBuildArtifact("secondprog")
@@ -52,10 +54,26 @@
             'Set breakpoint 2 here', lldb.SBFileSpec("secondprog.cpp", False))
         self.assertTrue(breakpoint2, VALID_BREAKPOINT)
 
-        # Launch the process
-        process = target.LaunchSimple(
-            None, None, self.get_process_working_directory())
-        self.assertTrue(process, PROCESS_IS_VALID)
+        if not should_attach:
+            # Launch the process
+            process = target.LaunchSimple(
+                None, None, self.get_process_working_directory())
+            self.assertTrue(process, PROCESS_IS_VALID)
+        else:
+            # Spawn the process and attach to it
+            popen = subprocess.Popen(exe, env={"LLDB_TEST_SHOULD_ATTACH": "1"})
+            if self.TraceOn():
+                print("Will attach to PID " + str(popen.pid))
+
+            error = lldb.SBError()
+            attach_info = lldb.SBAttachInfo(popen.pid)
+            process = target.Attach(attach_info, error)
+            self.assertTrue(error.Success() and process)
+
+            process.GetSelectedThread().GetSelectedFrame().EvaluateExpression(
+                "wait_for_attach = 0")
+
+            self.assertTrue(process.Continue())
 
         if self.TraceOn():
             self.runCmd("settings show target.process.stop-on-exec", check=False)
diff --git a/lldb/test/API/functionalities/exec/main.cpp b/lldb/test/API/functionalities/exec/main.cpp
--- a/lldb/test/API/functionalities/exec/main.cpp
+++ b/lldb/test/API/functionalities/exec/main.cpp
@@ -1,13 +1,24 @@
 #define _POSIX_C_SOURCE 200809L
 
+#include <chrono>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <libgen.h>
 #include <string>
+#include <thread>
 #include <unistd.h>
 
+volatile int wait_for_attach = 1;
+
 int main(int argc, char const **argv) {
+  if (getenv("LLDB_TEST_SHOULD_ATTACH") != nullptr) {
+    lldb_enable_attach();
+
+    while (wait_for_attach)
+      std::this_thread::sleep_for(std::chrono::milliseconds(10));
+  }
+
   char *buf = strdup(argv[0]); // Set breakpoint 1 here
   std::string directory_name(::dirname(buf));