Index: lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.h
===================================================================
--- lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.h
+++ lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.h
@@ -14,6 +14,7 @@
 // clang-format off
 #include <sys/param.h>
 #include <sys/types.h>
+#include <sys/ptrace.h>
 #include <machine/reg.h>
 // clang-format on
 
@@ -21,6 +22,10 @@
 #include "Plugins/Process/Utility/RegisterContext_x86.h"
 #include "Plugins/Process/Utility/lldb-x86-register-enums.h"
 
+#if defined(PT_GETXSTATE) && defined(PT_SETXSTATE)
+#define HAVE_XSTATE
+#endif
+
 namespace lldb_private {
 namespace process_netbsd {
 
@@ -68,12 +73,15 @@
 
 private:
   // Private member types.
-  enum { GPRegSet, FPRegSet, DBRegSet };
+  enum { GPRegSet, FPRegSet, DBRegSet, XStateRegSet };
 
   // Private member variables.
   struct reg m_gpr_x86_64;
   struct fpreg m_fpr_x86_64;
   struct dbreg m_dbr_x86_64;
+#ifdef HAVE_XSTATE
+  struct xstate m_xstate_x86_64;
+#endif
 
   int GetSetForNativeRegNum(int reg_num) const;
 
Index: lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp
===================================================================
--- lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp
+++ lldb/trunk/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp
@@ -22,7 +22,10 @@
 #include <sys/types.h>
 #include <sys/ptrace.h>
 #include <sys/sysctl.h>
+#include <sys/uio.h>
 #include <x86/cpu.h>
+#include <x86/cpu_extended_state.h>
+#include <x86/specialreg.h>
 #include <elf.h>
 #include <err.h>
 #include <stdint.h>
@@ -148,7 +151,7 @@
   else if (reg_num <= k_last_fpr_x86_64)
     return FPRegSet;
   else if (reg_num <= k_last_avx_x86_64)
-    return -1; // AVX
+    return XStateRegSet; // AVX
   else if (reg_num <= k_last_mpxr_x86_64)
     return -1; // MPXR
   else if (reg_num <= k_last_mpxc_x86_64)
@@ -167,6 +170,15 @@
     return DoRegisterSet(PT_GETFPREGS, &m_fpr_x86_64);
   case DBRegSet:
     return DoRegisterSet(PT_GETDBREGS, &m_dbr_x86_64);
+  case XStateRegSet:
+#ifdef HAVE_XSTATE
+    {
+      struct iovec iov = {&m_xstate_x86_64, sizeof(m_xstate_x86_64)};
+      return DoRegisterSet(PT_GETXSTATE, &iov);
+    }
+#else
+    return Status("XState is not supported by the kernel");
+#endif
   }
   llvm_unreachable("NativeRegisterContextNetBSD_x86_64::ReadRegisterSet");
 }
@@ -179,6 +191,15 @@
     return DoRegisterSet(PT_SETFPREGS, &m_fpr_x86_64);
   case DBRegSet:
     return DoRegisterSet(PT_SETDBREGS, &m_dbr_x86_64);
+  case XStateRegSet:
+#ifdef HAVE_XSTATE
+    {
+      struct iovec iov = {&m_xstate_x86_64, sizeof(m_xstate_x86_64)};
+      return DoRegisterSet(PT_SETXSTATE, &iov);
+    }
+#else
+    return Status("XState is not supported by the kernel");
+#endif
   }
   llvm_unreachable("NativeRegisterContextNetBSD_x86_64::WriteRegisterSet");
 }
@@ -360,6 +381,39 @@
     reg_value.SetBytes(&m_fpr_x86_64.fxstate.fx_xmm[reg - lldb_xmm0_x86_64],
                        reg_info->byte_size, endian::InlHostByteOrder());
     break;
+  case lldb_ymm0_x86_64:
+  case lldb_ymm1_x86_64:
+  case lldb_ymm2_x86_64:
+  case lldb_ymm3_x86_64:
+  case lldb_ymm4_x86_64:
+  case lldb_ymm5_x86_64:
+  case lldb_ymm6_x86_64:
+  case lldb_ymm7_x86_64:
+  case lldb_ymm8_x86_64:
+  case lldb_ymm9_x86_64:
+  case lldb_ymm10_x86_64:
+  case lldb_ymm11_x86_64:
+  case lldb_ymm12_x86_64:
+  case lldb_ymm13_x86_64:
+  case lldb_ymm14_x86_64:
+  case lldb_ymm15_x86_64:
+#ifdef HAVE_XSTATE
+    if (!(m_xstate_x86_64.xs_rfbm & XCR0_SSE) ||
+        !(m_xstate_x86_64.xs_rfbm & XCR0_YMM_Hi128)) {
+      error.SetErrorStringWithFormat("register \"%s\" not supported by CPU/kernel",
+                                     reg_info->name);
+    } else {
+      uint32_t reg_index = reg - lldb_ymm0_x86_64;
+      YMMReg ymm = XStateToYMM(
+          m_xstate_x86_64.xs_fxsave.fx_xmm[reg_index].xmm_bytes,
+          m_xstate_x86_64.xs_ymm_hi128.xs_ymm[reg_index].ymm_bytes);
+      reg_value.SetBytes(ymm.bytes, reg_info->byte_size,
+                         endian::InlHostByteOrder());
+    }
+#else
+    error.SetErrorString("XState queries not supported by the kernel");
+#endif
+    break;
   case lldb_dr0_x86_64:
   case lldb_dr1_x86_64:
   case lldb_dr2_x86_64:
@@ -552,6 +606,39 @@
     ::memcpy(&m_fpr_x86_64.fxstate.fx_xmm[reg - lldb_xmm0_x86_64],
              reg_value.GetBytes(), reg_value.GetByteSize());
     break;
+  case lldb_ymm0_x86_64:
+  case lldb_ymm1_x86_64:
+  case lldb_ymm2_x86_64:
+  case lldb_ymm3_x86_64:
+  case lldb_ymm4_x86_64:
+  case lldb_ymm5_x86_64:
+  case lldb_ymm6_x86_64:
+  case lldb_ymm7_x86_64:
+  case lldb_ymm8_x86_64:
+  case lldb_ymm9_x86_64:
+  case lldb_ymm10_x86_64:
+  case lldb_ymm11_x86_64:
+  case lldb_ymm12_x86_64:
+  case lldb_ymm13_x86_64:
+  case lldb_ymm14_x86_64:
+  case lldb_ymm15_x86_64:
+#ifdef HAVE_XSTATE
+    if (!(m_xstate_x86_64.xs_rfbm & XCR0_SSE) ||
+        !(m_xstate_x86_64.xs_rfbm & XCR0_YMM_Hi128)) {
+      error.SetErrorStringWithFormat("register \"%s\" not supported by CPU/kernel",
+                                     reg_info->name);
+    } else {
+      uint32_t reg_index = reg - lldb_ymm0_x86_64;
+      YMMReg ymm;
+      ::memcpy(ymm.bytes, reg_value.GetBytes(), reg_value.GetByteSize());
+      YMMToXState(ymm,
+          m_xstate_x86_64.xs_fxsave.fx_xmm[reg_index].xmm_bytes,
+          m_xstate_x86_64.xs_ymm_hi128.xs_ymm[reg_index].ymm_bytes);
+    }
+#else
+    error.SetErrorString("XState not supported by the kernel");
+#endif
+    break;
   case lldb_dr0_x86_64:
   case lldb_dr1_x86_64:
   case lldb_dr2_x86_64: