diff --git a/lldb/include/lldb/API/SBHostOS.h b/lldb/include/lldb/API/SBHostOS.h
--- a/lldb/include/lldb/API/SBHostOS.h
+++ b/lldb/include/lldb/API/SBHostOS.h
@@ -24,15 +24,26 @@
 
   static lldb::SBFileSpec GetUserHomeDirectory();
 
+  LLDB_DEPRECATED("Threading functionality in SBHostOS is not well supported, "
+                  "not portable, and is difficult to use from Python.")
   static void ThreadCreated(const char *name);
 
+  LLDB_DEPRECATED("Threading functionality in SBHostOS is not well supported, "
+                  "not portable, and is difficult to use from Python.")
   static lldb::thread_t ThreadCreate(const char *name,
                                      lldb::thread_func_t thread_function,
                                      void *thread_arg, lldb::SBError *err);
 
+  LLDB_DEPRECATED("Threading functionality in SBHostOS is not well supported, "
+                  "not portable, and is difficult to use from Python.")
   static bool ThreadCancel(lldb::thread_t thread, lldb::SBError *err);
 
+  LLDB_DEPRECATED("Threading functionality in SBHostOS is not well supported, "
+                  "not portable, and is difficult to use from Python.")
   static bool ThreadDetach(lldb::thread_t thread, lldb::SBError *err);
+
+  LLDB_DEPRECATED("Threading functionality in SBHostOS is not well supported, "
+                  "not portable, and is difficult to use from Python.")
   static bool ThreadJoin(lldb::thread_t thread, lldb::thread_result_t *result,
                          lldb::SBError *err);
 
diff --git a/lldb/tools/driver/Driver.cpp b/lldb/tools/driver/Driver.cpp
--- a/lldb/tools/driver/Driver.cpp
+++ b/lldb/tools/driver/Driver.cpp
@@ -795,8 +795,6 @@
   // Setup LLDB signal handlers once the debugger has been initialized.
   SBDebugger::PrintDiagnosticsOnError();
 
-  SBHostOS::ThreadCreated("<lldb.driver.main-thread>");
-
   signal(SIGINT, sigint_handler);
 #if !defined(_WIN32)
   signal(SIGPIPE, SIG_IGN);