Index: lib/Target/Mips/MicroMips32r6InstrFormats.td
===================================================================
--- lib/Target/Mips/MicroMips32r6InstrFormats.td
+++ lib/Target/Mips/MicroMips32r6InstrFormats.td
@@ -126,3 +126,17 @@
 
   string DecoderMethod = "DecodeMMR6LlSc";
 }
+
+class POOL32A_BITSWAP_FM_MMR6<bits<6> funct> : MipsR6Inst {
+  bits<5> rd;
+  bits<5> rt;
+
+  bits<32> Inst;
+
+  let Inst{31-26} = 0b000000;
+  let Inst{25-21} = rt;
+  let Inst{20-16} = rd;
+  let Inst{15-12} = 0b0000;
+  let Inst{11-6}  = funct;
+  let Inst{5-0}   = 0b111100;
+}
Index: lib/Target/Mips/MicroMips32r6InstrInfo.td
===================================================================
--- lib/Target/Mips/MicroMips32r6InstrInfo.td
+++ lib/Target/Mips/MicroMips32r6InstrInfo.td
@@ -24,6 +24,7 @@
 class ADDIUPC_MMR6_ENC : PCREL19_FM_MMR6<0b00>;
 class BALC_MMR6_ENC  : BRANCH_OFF26_FM<0b101101>;
 class BC_MMR6_ENC : BRANCH_OFF26_FM<0b100101>;
+class BITSWAP_MMR6_ENC : POOL32A_BITSWAP_FM_MMR6<0b101100>;
 class CLO_MMR6_ENC : POOL32A_2R_FM_MMR6<0b0100101100>;
 class CLZ_MMR6_ENC : SPECIAL_2R_FM_MMR6<0b010000>;
 class JIALC_MMR6_ENC : JMP_IDX_COMPACT_FM<0b101001>;
@@ -96,6 +97,16 @@
 }
 class BC_MMR6_DESC : BC_MMR6_DESC_BASE<"bc", brtarget26>;
 
+class BITSWAP_MMR6_DESC_BASE<string instr_asm, RegisterOperand GPROpnd>
+    : MMR6Arch<instr_asm> {
+  dag OutOperandList = (outs GPROpnd:$rd);
+  dag InOperandList = (ins GPROpnd:$rt);
+  string AsmString = !strconcat(instr_asm, "\t$rd, $rt");
+  list<dag> Pattern = [];
+}
+
+class BITSWAP_MMR6_DESC : BITSWAP_MMR6_DESC_BASE<"bitswap", GPR32Opnd>;
+
 class CLO_CLZ_MMR6_DESC_BASE<string instr_asm, RegisterOperand GPROpnd>
     : MMR6Arch<instr_asm> {
   dag OutOperandList = (outs GPROpnd:$rt);
@@ -178,6 +189,8 @@
                    ISA_MICROMIPS32R6;
 def BALC_MMR6 : R6MMR6Rel, BALC_MMR6_ENC, BALC_MMR6_DESC, ISA_MICROMIPS32R6;
 def BC_MMR6 : R6MMR6Rel, BC_MMR6_ENC, BC_MMR6_DESC, ISA_MICROMIPS32R6;
+def BITSWAP_MMR6 : R6MMR6Rel, BITSWAP_MMR6_ENC, BITSWAP_MMR6_DESC,
+                   ISA_MICROMIPS32R6;
 def CLO_MMR6 : R6MMR6Rel, CLO_MMR6_ENC, CLO_MMR6_DESC, ISA_MICROMIPS32R6;
 def CLZ_MMR6 : R6MMR6Rel, CLZ_MMR6_ENC, CLZ_MMR6_DESC, ISA_MICROMIPS32R6;
 def JIALC_MMR6 : R6MMR6Rel, JIALC_MMR6_ENC, JIALC_MMR6_DESC, ISA_MICROMIPS32R6;
Index: lib/Target/Mips/Mips32r6InstrInfo.td
===================================================================
--- lib/Target/Mips/Mips32r6InstrInfo.td
+++ lib/Target/Mips/Mips32r6InstrInfo.td
@@ -404,7 +404,8 @@
   bit isBarrier=1;
 }
 
-class BITSWAP_DESC_BASE<string instr_asm, RegisterOperand GPROpnd> {
+class BITSWAP_DESC_BASE<string instr_asm, RegisterOperand GPROpnd>
+    : MipsR6Arch<instr_asm> {
   dag OutOperandList = (outs GPROpnd:$rd);
   dag InOperandList = (ins GPROpnd:$rt);
   string AsmString = !strconcat(instr_asm, "\t$rd, $rt");
@@ -671,7 +672,7 @@
 def BGEZC : BGEZC_ENC, BGEZC_DESC, ISA_MIPS32R6;
 def BGTZALC : BGTZALC_ENC, BGTZALC_DESC, ISA_MIPS32R6;
 def BGTZC : BGTZC_ENC, BGTZC_DESC, ISA_MIPS32R6;
-def BITSWAP : BITSWAP_ENC, BITSWAP_DESC, ISA_MIPS32R6;
+def BITSWAP : R6MMR6Rel, BITSWAP_ENC, BITSWAP_DESC, ISA_MIPS32R6;
 def BLEZALC : BLEZALC_ENC, BLEZALC_DESC, ISA_MIPS32R6;
 def BLEZC : BLEZC_ENC, BLEZC_DESC, ISA_MIPS32R6;
 def BLTC : BLTC_ENC, BLTC_DESC, ISA_MIPS32R6;
Index: test/MC/Disassembler/Mips/micromips32r6.txt
===================================================================
--- test/MC/Disassembler/Mips/micromips32r6.txt
+++ test/MC/Disassembler/Mips/micromips32r6.txt
@@ -21,6 +21,9 @@
 # CHECK: bc 14572256
 0x94 0x37 0x96 0xb8
 
+# CHECK: bitswap $4, $2
+0x00 0x44 0x0b 0x3c
+
 # CHECK: clo $11, $5
 0x01 0x65 0x4b 0x3c
 
Index: test/MC/Mips/micromips32r6/valid.s
===================================================================
--- test/MC/Mips/micromips32r6/valid.s
+++ test/MC/Mips/micromips32r6/valid.s
@@ -8,6 +8,7 @@
   addiupc $4, 100          # CHECK: addiupc $4, 100     # encoding: [0x78,0x80,0x00,0x19]
   balc 14572256            # CHECK: balc 14572256       # encoding: [0xb4,0x37,0x96,0xb8]
   bc 14572256              # CHECK: bc 14572256         # encoding: [0x94,0x37,0x96,0xb8]
+  bitswap $4, $2           # CHECK: bitswap $4, $2      # encoding: [0x00,0x44,0x0b,0x3c]
   clo $11, $a1             # CHECK: clo $11, $5         # encoding: [0x01,0x65,0x4b,0x3c]
   clz $sp, $gp             # CHECK: clz $sp, $gp        # encoding: [0x03,0x80,0xe8,0x50]
   jialc $5, 256            # CHECK: jialc $5, 256       # encoding: [0xa4,0x05,0x01,0x00]