diff --git a/lldb/include/lldb/Target/ThreadList.h b/lldb/include/lldb/Target/ThreadList.h
index 263d26a033e1..2ebcd0b0e2c9 100644
--- a/lldb/include/lldb/Target/ThreadList.h
+++ b/lldb/include/lldb/Target/ThreadList.h
@@ -102,8 +102,6 @@ public:
 
   lldb::ThreadSP GetThreadSPForThreadPtr(Thread *thread_ptr);
 
-  lldb::ThreadSP GetBackingThread(const lldb::ThreadSP &real_thread);
-
   bool ShouldStop(Event *event_ptr);
 
   Vote ShouldReportStop(Event *event_ptr);
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestThreadSelectionBug.py b/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestThreadSelectionBug.py
deleted file mode 100644
index 400a93661033..000000000000
--- a/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/TestThreadSelectionBug.py
+++ /dev/null
@@ -1,50 +0,0 @@
-from __future__ import print_function
-import lldb
-from lldbsuite.test.lldbtest import *
-from lldbsuite.test.decorators import *
-from gdbclientutils import *
-
-
-class TestThreadSelectionBug(GDBRemoteTestBase):
-    def test(self):
-        class MyResponder(MockGDBServerResponder):
-            def cont(self):
-                # Simulate process stopping due to a raise(SIGINT)
-                return "T01reason:signal"
-
-        self.server.responder = MyResponder()
-        target = self.createTarget("a.yaml")
-        process = self.connect(target)
-        python_os_plugin_path = os.path.join(self.getSourceDir(),
-                                             'operating_system.py')
-        command = "settings set target.process.python-os-plugin-path '{}'".format(
-            python_os_plugin_path)
-        self.dbg.HandleCommand(command)
-
-        self.assertTrue(process, PROCESS_IS_VALID)
-        self.assertEqual(process.GetNumThreads(), 3)
-
-        # Verify our OS plug-in threads showed up
-        thread = process.GetThreadByID(0x1)
-        self.assertTrue(
-            thread.IsValid(),
-            "Make sure there is a thread 0x1 after we load the python OS plug-in")
-        thread = process.GetThreadByID(0x2)
-        self.assertTrue(
-            thread.IsValid(),
-            "Make sure there is a thread 0x2 after we load the python OS plug-in")
-        thread = process.GetThreadByID(0x3)
-        self.assertTrue(
-            thread.IsValid(),
-            "Make sure there is a thread 0x3 after we load the python OS plug-in")
-
-        # Verify that a thread other than 3 is selected.
-        thread = process.GetSelectedThread()
-        self.assertNotEqual(thread.GetThreadID(), 0x3)
-
-        # Verify that we select the thread backed by physical thread 1, rather
-        # than virtual thread 1. The mapping comes from the OS plugin, where we
-        # specified that thread 3 is backed by real thread 1.
-        process.Continue()
-        thread = process.GetSelectedThread()
-        self.assertEqual(thread.GetThreadID(), 0x3)
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/operating_system.py b/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/operating_system.py
deleted file mode 100644
index ad9b6fd4e55a..000000000000
--- a/lldb/packages/Python/lldbsuite/test/functionalities/gdb_remote_client/operating_system.py
+++ /dev/null
@@ -1,45 +0,0 @@
-import lldb
-import struct
-
-
-class OperatingSystemPlugIn(object):
-    """Class that provides data for an instance of a LLDB 'OperatingSystemPython' plug-in class"""
-
-    def __init__(self, process):
-        '''Initialization needs a valid.SBProcess object.
-
-        This plug-in will get created after a live process is valid and has stopped for the first time.
-        '''
-        self.process = None
-        self.registers = None
-        self.threads = None
-        if isinstance(process, lldb.SBProcess) and process.IsValid():
-            self.process = process
-            self.threads = None  # Will be an dictionary containing info for each thread
-
-    def get_target(self):
-        return self.process.target
-
-    def get_thread_info(self):
-        if not self.threads:
-            self.threads = [{
-                'tid': 0x1,
-                'name': 'one',
-                'queue': 'queue1',
-                'state': 'stopped',
-                'stop_reason': 'none'
-            }, {
-                'tid': 0x2,
-                'name': 'two',
-                'queue': 'queue2',
-                'state': 'stopped',
-                'stop_reason': 'none'
-            }, {
-                'tid': 0x3,
-                'name': 'three',
-                'queue': 'queue3',
-                'state': 'stopped',
-                'stop_reason': 'sigstop',
-                'core': 0
-            }]
-        return self.threads
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 0fb97b2f7db4..fc5f79e3544a 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -1822,9 +1822,10 @@ ThreadSP ProcessGDBRemote::SetThreadStopInfo(
       if (!thread_sp->StopInfoIsUpToDate()) {
         thread_sp->SetStopInfo(StopInfoSP());
         // If there's a memory thread backed by this thread, we need to use it
-        // to calculate StopInfo.
-        if (ThreadSP memory_thread_sp =
-                m_thread_list.GetBackingThread(thread_sp))
+        // to calcualte StopInfo.
+        ThreadSP memory_thread_sp =
+            m_thread_list.FindThreadByProtocolID(thread_sp->GetProtocolID());
+        if (memory_thread_sp)
           thread_sp = memory_thread_sp;
 
         if (exc_type != 0) {
diff --git a/lldb/source/Target/ThreadList.cpp b/lldb/source/Target/ThreadList.cpp
index 614839146447..4cf8f9061a89 100644
--- a/lldb/source/Target/ThreadList.cpp
+++ b/lldb/source/Target/ThreadList.cpp
@@ -195,20 +195,6 @@ ThreadSP ThreadList::GetThreadSPForThreadPtr(Thread *thread_ptr) {
   return thread_sp;
 }
 
-ThreadSP ThreadList::GetBackingThread(const ThreadSP &real_thread) {
-  std::lock_guard<std::recursive_mutex> guard(GetMutex());
-
-  ThreadSP thread_sp;
-  const uint32_t num_threads = m_threads.size();
-  for (uint32_t idx = 0; idx < num_threads; ++idx) {
-    if (m_threads[idx]->GetBackingThread() == real_thread) {
-      thread_sp = m_threads[idx];
-      break;
-    }
-  }
-  return thread_sp;
-}
-
 ThreadSP ThreadList::FindThreadByIndexID(uint32_t index_id, bool can_update) {
   std::lock_guard<std::recursive_mutex> guard(GetMutex());