Index: source/Plugins/Process/Windows/Common/TargetThreadWindows.h
===================================================================
--- source/Plugins/Process/Windows/Common/TargetThreadWindows.h
+++ source/Plugins/Process/Windows/Common/TargetThreadWindows.h
@@ -42,8 +42,7 @@
   HostThread GetHostThread() const { return m_host_thread; }
 
 private:
-  lldb::RegisterContextSP CreateRegisterContextForFrameIndex(uint32_t idx);
-
+  lldb::RegisterContextSP m_thread_reg_ctx_sp;
   HostThread m_host_thread;
 };
 }
Index: source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
===================================================================
--- source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
+++ source/Plugins/Process/Windows/Common/TargetThreadWindows.cpp
@@ -33,6 +33,7 @@
 TargetThreadWindows::TargetThreadWindows(ProcessWindows &process,
                                          const HostThread &thread)
     : Thread(process, thread.GetNativeThread().GetThreadId()),
+      m_thread_reg_ctx_sp(),
       m_host_thread(thread) {}
 
 TargetThreadWindows::~TargetThreadWindows() { DestroyThread(); }
@@ -48,41 +49,51 @@
 void TargetThreadWindows::DidStop() {}
 
 RegisterContextSP TargetThreadWindows::GetRegisterContext() {
-  if (!m_reg_context_sp)
-    m_reg_context_sp = CreateRegisterContextForFrameIndex(0);
+  if (m_reg_context_sp.get() == NULL)
+    m_reg_context_sp = CreateRegisterContextForFrame(NULL);
 
   return m_reg_context_sp;
 }
 
 RegisterContextSP
 TargetThreadWindows::CreateRegisterContextForFrame(StackFrame *frame) {
-  return CreateRegisterContextForFrameIndex(frame->GetConcreteFrameIndex());
-}
-
-RegisterContextSP
-TargetThreadWindows::CreateRegisterContextForFrameIndex(uint32_t idx) {
-  if (!m_reg_context_sp) {
-    ArchSpec arch = HostInfo::GetArchitecture();
-    switch (arch.GetMachine()) {
-    case llvm::Triple::x86:
+  RegisterContextSP reg_ctx_sp;
+  uint32_t concrete_frame_idx = 0;
+  Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
+
+  if (frame)
+    concrete_frame_idx = frame->GetConcreteFrameIndex();
+
+  if (concrete_frame_idx == 0) {
+    if (m_thread_reg_ctx_sp.get() == NULL) {
+      ArchSpec arch = HostInfo::GetArchitecture();
+      switch (arch.GetMachine()) {
+      case llvm::Triple::x86:
 #if defined(_WIN64)
-// FIXME: This is a Wow64 process, create a RegisterContextWindows_Wow64
+        // FIXME: This is a Wow64 process, create a RegisterContextWindows_Wow64
+        LLDB_LOG(log, "This is a Wow64 process, we should create a RegisterContextWindows_Wow64, but we don't.");
 #else
-      m_reg_context_sp.reset(new RegisterContextWindows_x86(*this, idx));
+        m_thread_reg_ctx_sp.reset(new RegisterContextWindows_x86(*this, concrete_frame_idx));
 #endif
-      break;
-    case llvm::Triple::x86_64:
+        break;
+      case llvm::Triple::x86_64:
 #if defined(_WIN64)
-      m_reg_context_sp.reset(new RegisterContextWindows_x64(*this, idx));
+        m_thread_reg_ctx_sp.reset(new RegisterContextWindows_x64(*this, concrete_frame_idx));
 #else
-// LLDB is 32-bit, but the target process is 64-bit.  We probably can't debug
-// this.
+        LLDB_LOG(log, "LLDB is 32-bit, but the target process is 64-bit.");
 #endif
-    default:
-      break;
+      default:
+        break;
+      }
     }
+    reg_ctx_sp = m_thread_reg_ctx_sp;
+  } else {
+    Unwind *unwinder = GetUnwinder();
+    if (unwinder)
+      reg_ctx_sp = unwinder->CreateRegisterContextForFrame(frame);
   }
-  return m_reg_context_sp;
+
+  return reg_ctx_sp;
 }
 
 bool TargetThreadWindows::CalculateStopInfo() {
Index: source/Plugins/Process/elf-core/ThreadElfCore.h
===================================================================
--- source/Plugins/Process/elf-core/ThreadElfCore.h
+++ source/Plugins/Process/elf-core/ThreadElfCore.h
@@ -146,8 +146,6 @@
   lldb::RegisterContextSP
   CreateRegisterContextForFrame(lldb_private::StackFrame *frame) override;
 
-  void ClearStackFrames() override;
-
   static bool ThreadIDIsValid(lldb::tid_t thread) { return thread != 0; }
 
   const char *GetName() override {
Index: source/Plugins/Process/elf-core/ThreadElfCore.cpp
===================================================================
--- source/Plugins/Process/elf-core/ThreadElfCore.cpp
+++ source/Plugins/Process/elf-core/ThreadElfCore.cpp
@@ -55,13 +55,6 @@
   GetRegisterContext()->InvalidateIfNeeded(false);
 }
 
-void ThreadElfCore::ClearStackFrames() {
-  Unwind *unwinder = GetUnwinder();
-  if (unwinder)
-    unwinder->Clear();
-  Thread::ClearStackFrames();
-}
-
 RegisterContextSP ThreadElfCore::GetRegisterContext() {
   if (m_reg_context_sp.get() == NULL) {
     m_reg_context_sp = CreateRegisterContextForFrame(NULL);
@@ -234,8 +227,10 @@
     }
 
     reg_ctx_sp = m_thread_reg_ctx_sp;
-  } else if (m_unwinder_ap.get()) {
-    reg_ctx_sp = m_unwinder_ap->CreateRegisterContextForFrame(frame);
+  } else {
+    Unwind *unwinder = GetUnwinder();
+    if (unwinder)
+      reg_ctx_sp = unwinder->CreateRegisterContextForFrame(frame);
   }
   return reg_ctx_sp;
 }