diff --git a/lib/Target/Mips/Disassembler/MipsDisassembler.cpp b/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
index 59e49d8ddc6..0dba33a2767 100644
--- a/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ b/lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -143,6 +143,16 @@ static DecodeStatus DecodeACRegsDSPRegisterClass(MCInst &Inst,
                                                  uint64_t Address,
                                                  const void *Decoder);
 
+static DecodeStatus DecodeHIRegsDSPRegisterClass(MCInst &Inst,
+                                                 unsigned RegNo,
+                                                 uint64_t Address,
+                                                 const void *Decoder);
+
+static DecodeStatus DecodeLORegsDSPRegisterClass(MCInst &Inst,
+                                                 unsigned RegNo,
+                                                 uint64_t Address,
+                                                 const void *Decoder);
+
 static DecodeStatus DecodeBranchTarget(MCInst &Inst,
                                        unsigned Offset,
                                        uint64_t Address,
@@ -496,6 +506,30 @@ static DecodeStatus DecodeACRegsDSPRegisterClass(MCInst &Inst,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeHIRegsDSPRegisterClass(MCInst &Inst,
+                                                 unsigned RegNo,
+                                                 uint64_t Address,
+                                                 const void *Decoder) {
+  if (RegNo >= 4)
+    return MCDisassembler::Fail;
+
+  unsigned Reg = getReg(Decoder, Mips::HIRegsDSPRegClassID, RegNo);
+  Inst.addOperand(MCOperand::CreateReg(Reg));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus DecodeLORegsDSPRegisterClass(MCInst &Inst,
+                                                 unsigned RegNo,
+                                                 uint64_t Address,
+                                                 const void *Decoder) {
+  if (RegNo >= 4)
+    return MCDisassembler::Fail;
+
+  unsigned Reg = getReg(Decoder, Mips::LORegsDSPRegClassID, RegNo);
+  Inst.addOperand(MCOperand::CreateReg(Reg));
+  return MCDisassembler::Success;
+}
+
 static DecodeStatus DecodeBranchTarget(MCInst &Inst,
                                        unsigned Offset,
                                        uint64_t Address,
diff --git a/lib/Target/Mips/MipsDSPInstrFormats.td b/lib/Target/Mips/MipsDSPInstrFormats.td
index a72a763fde0..cf09113cd8a 100644
--- a/lib/Target/Mips/MipsDSPInstrFormats.td
+++ b/lib/Target/Mips/MipsDSPInstrFormats.td
@@ -219,6 +219,33 @@ class MULT_FMT<bits<6> opcode, bits<6> funct> : DSPInst {
   let Inst{5-0} = funct;
 }
 
+// MFHI sub-class format.
+class MFHI_FMT<bits<6> funct> : DSPInst {
+  bits<5> rd;
+  bits<2> ac;
+
+  let Inst{31-26} = 0;
+  let Inst{25-23} = 0;
+  let Inst{22-21} = ac;
+  let Inst{20-16} = 0;
+  let Inst{15-11} = rd;
+  let Inst{10-6} = 0;
+  let Inst{5-0} = funct;
+}
+
+// MTHI sub-class format.
+class MTHI_FMT<bits<6> funct> : DSPInst {
+  bits<5> rs;
+  bits<2> ac;
+
+  let Inst{31-26} = 0;
+  let Inst{25-21} = rs;
+  let Inst{20-13} = 0;
+  let Inst{12-11} = ac;
+  let Inst{10-6} = 0;
+  let Inst{5-0} = funct;
+}
+
 // EXTR.W sub-class format (type 1).
 class EXTR_W_TY1_FMT<bits<5> op> : DSPInst {
   bits<5> rt;
diff --git a/lib/Target/Mips/MipsDSPInstrInfo.td b/lib/Target/Mips/MipsDSPInstrInfo.td
index df8ba9db9d2..86983dd4bcf 100644
--- a/lib/Target/Mips/MipsDSPInstrInfo.td
+++ b/lib/Target/Mips/MipsDSPInstrInfo.td
@@ -145,6 +145,10 @@ class MAQ_S_W_PHL_ENC : DPA_W_PH_FMT<0b10100>;
 class MAQ_S_W_PHR_ENC : DPA_W_PH_FMT<0b10110>;
 class MAQ_SA_W_PHL_ENC : DPA_W_PH_FMT<0b10000>;
 class MAQ_SA_W_PHR_ENC : DPA_W_PH_FMT<0b10010>;
+class MFHI_ENC : MFHI_FMT<0b010000>;
+class MFLO_ENC : MFHI_FMT<0b010010>;
+class MTHI_ENC : MTHI_FMT<0b010001>;
+class MTLO_ENC : MTHI_FMT<0b010011>;
 class DPAU_H_QBL_ENC : DPA_W_PH_FMT<0b00011>;
 class DPAU_H_QBR_ENC : DPA_W_PH_FMT<0b00111>;
 class DPSU_H_QBL_ENC : DPA_W_PH_FMT<0b01011>;
@@ -482,6 +486,20 @@ class MADD_DESC_BASE<string instr_asm, SDPatternOperator OpNode,
   string Constraints = "$acin = $ac";
 }
 
+class MFHI_DESC_BASE<string instr_asm, RegisterClass RC, InstrItinClass itin> {
+  dag OutOperandList = (outs CPURegs:$rd);
+  dag InOperandList = (ins RC:$ac);
+  string AsmString = !strconcat(instr_asm, "\t$rd, $ac");
+  InstrItinClass Itinerary = itin;
+}
+
+class MTHI_DESC_BASE<string instr_asm, RegisterClass RC, InstrItinClass itin> {
+  dag OutOperandList = (outs RC:$ac);
+  dag InOperandList = (ins CPURegs:$rs);
+  string AsmString = !strconcat(instr_asm, "\t$rs, $ac");
+  InstrItinClass Itinerary = itin;
+}
+
 class BPOSGE32_PSEUDO_DESC_BASE<SDPatternOperator OpNode, InstrItinClass itin> :
   MipsPseudo<(outs CPURegs:$dst), (ins), [(set CPURegs:$dst, (OpNode))]> {
   list<Register> Uses = [DSPCtrl];
@@ -725,6 +743,12 @@ class MAQ_SA_W_PHL_DESC : DPA_W_PH_DESC_BASE<"maq_sa.w.phl", MipsMAQ_SA_W_PHL>;
 
 class MAQ_SA_W_PHR_DESC : DPA_W_PH_DESC_BASE<"maq_sa.w.phr", MipsMAQ_SA_W_PHR>;
 
+// Move from/to hi/lo.
+class MFHI_DESC : MFHI_DESC_BASE<"mfhi", HIRegsDSP, NoItinerary>;
+class MFLO_DESC : MFHI_DESC_BASE<"mflo", LORegsDSP, NoItinerary>;
+class MTHI_DESC : MTHI_DESC_BASE<"mthi", HIRegsDSP, NoItinerary>;
+class MTLO_DESC : MTHI_DESC_BASE<"mtlo", LORegsDSP, NoItinerary>;
+
 // Dot product with accumulate/subtract
 class DPAU_H_QBL_DESC : DPA_W_PH_DESC_BASE<"dpau.h.qbl", MipsDPAU_H_QBL>;
 
@@ -1094,6 +1118,10 @@ def MAQ_S_W_PHL : MAQ_S_W_PHL_ENC, MAQ_S_W_PHL_DESC;
 def MAQ_S_W_PHR : MAQ_S_W_PHR_ENC, MAQ_S_W_PHR_DESC;
 def MAQ_SA_W_PHL : MAQ_SA_W_PHL_ENC, MAQ_SA_W_PHL_DESC;
 def MAQ_SA_W_PHR : MAQ_SA_W_PHR_ENC, MAQ_SA_W_PHR_DESC;
+def MFHI_DSP : MFHI_ENC, MFHI_DESC;
+def MFLO_DSP : MFLO_ENC, MFLO_DESC;
+def MTHI_DSP : MTHI_ENC, MTHI_DESC;
+def MTLO_DSP : MTLO_ENC, MTLO_DESC;
 def DPAU_H_QBL : DPAU_H_QBL_ENC, DPAU_H_QBL_DESC;
 def DPAU_H_QBR : DPAU_H_QBR_ENC, DPAU_H_QBR_DESC;
 def DPSU_H_QBL : DPSU_H_QBL_ENC, DPSU_H_QBL_DESC;
diff --git a/lib/Target/Mips/MipsRegisterInfo.td b/lib/Target/Mips/MipsRegisterInfo.td
index 64458bcef7e..30699ac4210 100644
--- a/lib/Target/Mips/MipsRegisterInfo.td
+++ b/lib/Target/Mips/MipsRegisterInfo.td
@@ -229,14 +229,14 @@ let Namespace = "Mips" in {
   def D31_64  : AFPR64<31, "f31", [F31]>, DwarfRegNum<[63]>;
 
   // Hi/Lo registers
-  def HI  : Register<"hi">, DwarfRegNum<[64]>;
-  def HI1 : Register<"hi1">, DwarfRegNum<[176]>;
-  def HI2 : Register<"hi2">, DwarfRegNum<[178]>;
-  def HI3 : Register<"hi3">, DwarfRegNum<[180]>;
-  def LO  : Register<"lo">, DwarfRegNum<[65]>;
-  def LO1 : Register<"lo1">, DwarfRegNum<[177]>;
-  def LO2 : Register<"lo2">, DwarfRegNum<[179]>;
-  def LO3 : Register<"lo3">, DwarfRegNum<[181]>;
+  def HI  : Register<"ac0">, DwarfRegNum<[64]>;
+  def HI1 : Register<"ac1">, DwarfRegNum<[176]>;
+  def HI2 : Register<"ac2">, DwarfRegNum<[178]>;
+  def HI3 : Register<"ac3">, DwarfRegNum<[180]>;
+  def LO  : Register<"ac0">, DwarfRegNum<[65]>;
+  def LO1 : Register<"ac1">, DwarfRegNum<[177]>;
+  def LO2 : Register<"ac2">, DwarfRegNum<[179]>;
+  def LO3 : Register<"ac3">, DwarfRegNum<[181]>;
 
   let SubRegIndices = [sub_32] in {
   def HI64  : RegisterWithSubRegs<"hi", [HI]>;
@@ -342,6 +342,8 @@ def CCR  : RegisterClass<"Mips", [i32], 32, (add FCR31,FCC0)>, Unallocatable;
 // Hi/Lo Registers
 def HILO : RegisterClass<"Mips", [i32], 32, (add HI, LO)>, Unallocatable;
 def HILO64 : RegisterClass<"Mips", [i64], 64, (add HI64, LO64)>, Unallocatable;
+def LORegsDSP : RegisterClass<"Mips", [i32], 32, (add LO, LO1, LO2, LO3)>;
+def HIRegsDSP : RegisterClass<"Mips", [i32], 32, (add HI, HI1, HI2, HI3)>;
 
 // Hardware registers
 def HWRegs : RegisterClass<"Mips", [i32], 32, (add HWR29)>, Unallocatable;
diff --git a/test/MC/Disassembler/Mips/mips-dsp.txt b/test/MC/Disassembler/Mips/mips-dsp.txt
new file mode 100644
index 00000000000..d10e62cd23c
--- /dev/null
+++ b/test/MC/Disassembler/Mips/mips-dsp.txt
@@ -0,0 +1,13 @@
+# RUN: llvm-mc -triple=mipsel-unknown-linux -mattr=+dsp -disassemble < %s | FileCheck %s
+
+# CHECK: mfhi $21, $ac3
+0x10 0xa8 0x60 0x00
+
+# CHECK: mflo $21, $ac3
+0x12 0xa8 0x60 0x00
+
+# CHECK: mthi $21, $ac3
+0x11 0x18 0xa0 0x02
+
+# CHECK: mtlo $21, $ac3
+0x13 0x18 0xa0 0x02