Index: lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
+++ lldb/trunk/lit/tools/lldb-mi/exec/exec-next.test
@@ -0,0 +1,30 @@
+# XFAIL: windows
+# -> llvm.org/pr24452
+#
+# RUN: %cc -o %t %p/inputs/main.c -g
+# RUN: %lldbmi %t < %s | FileCheck %s
+
+# Test lldb-mi -exec-next command.
+
+# Check that we have a valid target created via '%lldbmi %t'.
+# CHECK: ^done
+
+-break-insert main
+# CHECK: ^done,bkpt={number="1"
+
+-exec-run
+# CHECK: ^running
+# CHECK: *stopped,reason="breakpoint-hit"
+
+-exec-next --thread 0
+# Check that exec-next can process the case of invalid thread ID.
+# CHECK: ^error,msg="Command 'exec-next'. Thread ID invalid"
+
+-exec-next --thread 1
+# CHECK: ^running
+# CHECK: *stopped,reason="end-stepping-range"
+
+-exec-next
+# Check that exec-next can step over in a selected thread.
+# CHECK: ^running
+# CHECK: *stopped,reason="end-stepping-range"
Index: lldb/trunk/lit/tools/lldb-mi/exec/inputs/main.c
===================================================================
--- lldb/trunk/lit/tools/lldb-mi/exec/inputs/main.c
+++ lldb/trunk/lit/tools/lldb-mi/exec/inputs/main.c
@@ -0,0 +1,4 @@
+int main(void) {
+  int x = 0;
+  return x;
+}
Index: lldb/trunk/tools/lldb-mi/MICmdCmdExec.cpp
===================================================================
--- lldb/trunk/tools/lldb-mi/MICmdCmdExec.cpp
+++ lldb/trunk/tools/lldb-mi/MICmdCmdExec.cpp
@@ -22,6 +22,7 @@
 #include "lldb/API/SBCommandInterpreter.h"
 #include "lldb/API/SBProcess.h"
 #include "lldb/API/SBStream.h"
+#include "lldb/API/SBThread.h"
 #include "lldb/lldb-enumerations.h"
 
 // In-house headers:
@@ -378,12 +379,17 @@
 
   CMICmnLLDBDebugSessionInfo &rSessionInfo(
       CMICmnLLDBDebugSessionInfo::Instance());
-  lldb::SBDebugger &rDebugger = rSessionInfo.GetDebugger();
-  CMIUtilString strCmd("thread step-over");
-  if (nThreadId != UINT64_MAX)
-    strCmd += CMIUtilString::Format(" %llu", nThreadId);
-  rDebugger.GetCommandInterpreter().HandleCommand(strCmd.c_str(), m_lldbResult,
-                                                  false);
+
+  if (nThreadId != UINT64_MAX) {
+    lldb::SBThread sbThread = rSessionInfo.GetProcess().GetThreadByIndexID(nThreadId);
+    if (!sbThread.IsValid()) {
+      SetError(CMIUtilString::Format(MIRSRC(IDS_CMD_ERR_THREAD_INVALID),
+                                     m_cmdData.strMiCmd.c_str(),
+                                     m_constStrArgThread.c_str()));
+      return MIstatus::failure;
+    }
+    sbThread.StepOver();
+  } else rSessionInfo.GetProcess().GetSelectedThread().StepOver();
 
   return MIstatus::success;
 }