diff --git a/target/mips/translate.h b/target/mips/translate.h
index a807b3d2566..e4f2f26de89 100644
--- a/target/mips/translate.h
+++ b/target/mips/translate.h
@@ -185,5 +185,9 @@ bool decode_ase_mxu(DisasContext *ctx, uint32_t insn);
 /* decodetree generated */
 bool decode_isa_rel6(DisasContext *ctx, uint32_t insn);
 bool decode_ase_msa(DisasContext *ctx, uint32_t insn);
+bool decode_ext_txx9(DisasContext *ctx, uint32_t insn);
+#if defined(TARGET_MIPS64)
+bool decode_ext_tx79(DisasContext *ctx, uint32_t insn);
+#endif
 
 #endif
diff --git a/target/mips/tx79.decode b/target/mips/tx79.decode
new file mode 100644
index 00000000000..2e287ebbf36
--- /dev/null
+++ b/target/mips/tx79.decode
@@ -0,0 +1,25 @@
+# Toshiba C790's instruction set
+#
+# Copyright (C) 2021  Philippe Mathieu-Daudé
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+# Toshiba Appendix B  C790-Specific Instruction Set Details
+
+###########################################################################
+# Named attribute sets.  These are used to make nice(er) names
+# when creating helpers common to those for the individual
+# instruction patterns.
+
+&rtype           rs rt rd sa
+
+###########################################################################
+# Named instruction formats.  These are generally used to
+# reduce the amount of duplication between instruction patterns.
+
+@rd             ...... ..........  rd:5  ..... ......   &rtype rs=0 rt=0 sa=0
+
+###########################################################################
+
+MFHI1           011100 0000000000  ..... 00000 010000   @rd
+MFLO1           011100 0000000000  ..... 00000 010010   @rd
diff --git a/target/mips/translate.c b/target/mips/translate.c
index 9b08785f2b8..aa35d0f680e 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -1360,9 +1360,7 @@ enum {
     MMI_OPC_PLZCW      = 0x04 | MMI_OPC_CLASS_MMI,
     MMI_OPC_CLASS_MMI0 = 0x08 | MMI_OPC_CLASS_MMI,
     MMI_OPC_CLASS_MMI2 = 0x09 | MMI_OPC_CLASS_MMI,
-    MMI_OPC_MFHI1      = 0x10 | MMI_OPC_CLASS_MMI, /* Same minor as OPC_MFHI */
     MMI_OPC_MTHI1      = 0x11 | MMI_OPC_CLASS_MMI, /* Same minor as OPC_MTHI */
-    MMI_OPC_MFLO1      = 0x12 | MMI_OPC_CLASS_MMI, /* Same minor as OPC_MFLO */
     MMI_OPC_MTLO1      = 0x13 | MMI_OPC_CLASS_MMI, /* Same minor as OPC_MTLO */
     MMI_OPC_MULT1      = 0x18 | MMI_OPC_CLASS_MMI, /* Same minor as OPC_MULT */
     MMI_OPC_MULTU1     = 0x19 | MMI_OPC_CLASS_MMI, /* Same min. as OPC_MULTU */
@@ -3469,12 +3467,6 @@ static void gen_shift(DisasContext *ctx, uint32_t opc,
 static void gen_HILO1_tx79(DisasContext *ctx, uint32_t opc, int reg)
 {
     switch (opc) {
-    case MMI_OPC_MFHI1:
-        gen_store_gpr(cpu_HI[1], reg);
-        break;
-    case MMI_OPC_MFLO1:
-        gen_store_gpr(cpu_LO[1], reg);
-        break;
     case MMI_OPC_MTHI1:
         gen_load_gpr(cpu_HI[1], reg);
         break;
@@ -25120,10 +25112,6 @@ static void decode_mmi(CPUMIPSState *env, DisasContext *ctx)
     case MMI_OPC_MTHI1:
         gen_HILO1_tx79(ctx, opc, rs);
         break;
-    case MMI_OPC_MFLO1:
-    case MMI_OPC_MFHI1:
-        gen_HILO1_tx79(ctx, opc, rd);
-        break;
     case MMI_OPC_PLZCW:         /* TODO: MMI_OPC_PLZCW */
     case MMI_OPC_PMFHL:         /* TODO: MMI_OPC_PMFHL */
     case MMI_OPC_PMTHL:         /* TODO: MMI_OPC_PMTHL */
@@ -26095,6 +26083,9 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
     if (cpu_supports_isa(env, ISA_MIPS_R6) && decode_isa_rel6(ctx, ctx->opcode)) {
         return;
     }
+    if (cpu_supports_isa(env, INSN_R5900) && decode_ext_txx9(ctx, ctx->opcode)) {
+        return;
+    }
 
     if (decode_opc_legacy(env, ctx)) {
         return;
diff --git a/target/mips/tx79_translate.c b/target/mips/tx79_translate.c
new file mode 100644
index 00000000000..22bd6033e55
--- /dev/null
+++ b/target/mips/tx79_translate.c
@@ -0,0 +1,37 @@
+/*
+ * Toshiba TX79-specific instructions translation routines
+ *
+ *  Copyright (c) 2018 Fredrik Noring
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "tcg/tcg-op.h"
+#include "exec/helper-gen.h"
+#include "translate.h"
+
+/* Include the auto-generated decoder.  */
+#include "decode-tx79.c.inc"
+
+bool decode_ext_tx79(DisasContext *ctx, uint32_t insn)
+{
+    if (TARGET_LONG_BITS == 64 && decode_tx79(ctx, insn)) {
+        return true;
+    }
+    return false;
+}
+
+static bool trans_MFHI1(DisasContext *ctx, arg_rtype *a)
+{
+    gen_store_gpr(cpu_HI[1], a->rd);
+
+    return true;
+}
+
+static bool trans_MFLO1(DisasContext *ctx, arg_rtype *a)
+{
+    gen_store_gpr(cpu_LO[1], a->rd);
+
+    return true;
+}
diff --git a/target/mips/txx9_translate.c b/target/mips/txx9_translate.c
new file mode 100644
index 00000000000..8a2c0b766bd
--- /dev/null
+++ b/target/mips/txx9_translate.c
@@ -0,0 +1,20 @@
+/*
+ * Toshiba TXx9 instructions translation routines
+ *
+ *  Copyright (c) 2021 Philippe Mathieu-Daudé
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "translate.h"
+
+bool decode_ext_txx9(DisasContext *ctx, uint32_t insn)
+{
+#if defined(TARGET_MIPS64)
+    if (decode_ext_tx79(ctx, insn)) {
+        return true;
+    }
+#endif
+    return false;
+}
diff --git a/target/mips/meson.build b/target/mips/meson.build
index 4a951e522d4..3b131c4a7f6 100644
--- a/target/mips/meson.build
+++ b/target/mips/meson.build
@@ -3,6 +3,7 @@
   decodetree.process('mips64r6.decode', extra_args: '--static-decode=decode_mips64r6'),
   decodetree.process('msa32.decode', extra_args: '--static-decode=decode_msa32'),
   decodetree.process('msa64.decode', extra_args: '--static-decode=decode_msa64'),
+  decodetree.process('tx79.decode', extra_args: '--static-decode=decode_tx79'),
 ]
 
 mips_ss = ss.source_set()
@@ -23,6 +24,10 @@
   'tlb_helper.c',
   'translate.c',
   'translate_addr_const.c',
+  'txx9_translate.c',
+))
+mips_ss.add(when: ['CONFIG_TCG', 'TARGET_MIPS64'], if_true: files(
+  'tx79_translate.c',
 ))
 mips_tcg_ss.add(when: 'TARGET_MIPS64', if_false: files(
   'mxu_translate.c',
