Index: lib/Target/Mips/Disassembler/MipsDisassembler.cpp
===================================================================
--- lib/Target/Mips/Disassembler/MipsDisassembler.cpp
+++ lib/Target/Mips/Disassembler/MipsDisassembler.cpp
@@ -252,6 +252,11 @@
                               uint64_t Address,
                               const void *Decoder);
 
+static DecodeStatus DecodeSyncI(MCInst &Inst,
+                              unsigned Insn,
+                              uint64_t Address,
+                              const void *Decoder);
+
 static DecodeStatus DecodeMSA128Mem(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder);
 
@@ -1045,6 +1050,21 @@
   return MCDisassembler::Success;
 }
 
+static DecodeStatus DecodeSyncI(MCInst &Inst,
+                              unsigned Insn,
+                              uint64_t Address,
+                              const void *Decoder) {
+  int Offset = SignExtend32<16>(Insn & 0xffff);
+  unsigned Base = fieldFromInstruction(Insn, 21, 5);
+
+  Base = getReg(Decoder, Mips::GPR32RegClassID, Base);
+
+  Inst.addOperand(MCOperand::CreateReg(Base));
+  Inst.addOperand(MCOperand::CreateImm(Offset));
+
+  return MCDisassembler::Success;
+}
+
 static DecodeStatus DecodeMSA128Mem(MCInst &Inst, unsigned Insn,
                                     uint64_t Address, const void *Decoder) {
   int Offset = SignExtend32<10>(fieldFromInstruction(Insn, 16, 10));
Index: lib/Target/Mips/MipsInstrFormats.td
===================================================================
--- lib/Target/Mips/MipsInstrFormats.td
+++ lib/Target/Mips/MipsInstrFormats.td
@@ -411,6 +411,19 @@
   let Inst{5-0}   = 0xf;
 }
 
+class SYNCI_FM : StdArch {
+  bits<21> addr; // produced by the mem_simm16 address as reg << 16 | imm (see getMemEncoding)
+  bits<5> rs = addr{20-16};
+  bits<16> offset = addr{15-0};
+
+  bits<32> Inst;
+
+  let Inst{31-26} = 0b000001;
+  let Inst{25-21} = rs;
+  let Inst{20-16} = 0b11111;
+  let Inst{15-0}  = offset;
+}
+
 class MULT_FM<bits<6> op, bits<6> funct> : StdArch {
   bits<5>  rs;
   bits<5>  rt;
Index: lib/Target/Mips/MipsInstrInfo.td
===================================================================
--- lib/Target/Mips/MipsInstrInfo.td
+++ lib/Target/Mips/MipsInstrInfo.td
@@ -428,6 +428,15 @@
   //let DiagnosticType = "Simm11";
 }
 
+def MipsMemSimm16AsmOperand : AsmOperandClass {
+  let Name = "MemOffsetSimm16";
+  let SuperClasses = [MipsMemAsmOperand];
+  let RenderMethod = "addMemOperands";
+  let ParserMethod = "parseMemOperand";
+  let PredicateMethod = "isMemWithSimmOffset<16>";
+  //let DiagnosticType = "Simm16";
+}
+
 def MipsInvertedImmoperand : AsmOperandClass {
   let Name = "InvNum";
   let RenderMethod = "addImmOperands";
@@ -470,6 +479,12 @@
   let ParserMatchClass = MipsMemSimm11AsmOperand;
 }
 
+def mem_simm16 : mem_generic {
+  let MIOperandInfo = (ops ptr_rc, simm16);
+  let EncoderMethod = "getMemEncoding";
+  let ParserMatchClass = MipsMemSimm16AsmOperand;
+}
+
 def mem_ea : Operand<iPTR> {
   let PrintMethod = "printMemOperandEA";
   let MIOperandInfo = (ops ptr_rc, simm16);
@@ -860,6 +875,13 @@
   InstSE<(outs), (ins i32imm:$stype), "sync $stype", [(MipsSync imm:$stype)],
          NoItinerary, FrmOther, opstr>;
 
+class SYNCI_FT<string opstr> :
+  InstSE<(outs), (ins mem_simm16:$addr), !strconcat(opstr, "\t$addr"), [],
+         NoItinerary, FrmOther, opstr> {
+  let hasSideEffects = 1;
+  let DecoderMethod = "DecodeSyncI";
+}
+
 let hasSideEffects = 1 in
 class TEQ_FT<string opstr, RegisterOperand RO> :
   InstSE<(outs), (ins RO:$rs, RO:$rt, uimm16:$code_),
@@ -1209,6 +1231,7 @@
 }
 
 def SYNC : MMRel, SYNC_FT<"sync">, SYNC_FM, ISA_MIPS32;
+def SYNCI : MMRel, SYNCI_FT<"synci">, SYNCI_FM, ISA_MIPS32R2;
 
 def TEQ : MMRel, TEQ_FT<"teq", GPR32Opnd>, TEQ_FM<0x34>, ISA_MIPS2;
 def TGE : MMRel, TEQ_FT<"tge", GPR32Opnd>, TEQ_FM<0x30>, ISA_MIPS2;
Index: test/MC/Disassembler/Mips/mips32r2.txt
===================================================================
--- test/MC/Disassembler/Mips/mips32r2.txt
+++ test/MC/Disassembler/Mips/mips32r2.txt
@@ -448,3 +448,6 @@
 
 # CHECK: xori  $9,  $6, 17767
 0x38 0xc9 0x45 0x67
+
+# CHECK: synci -6137($fp)
+0x07 0xdf 0xe8 0x07
Index: test/MC/Disassembler/Mips/mips32r2_le.txt
===================================================================
--- test/MC/Disassembler/Mips/mips32r2_le.txt
+++ test/MC/Disassembler/Mips/mips32r2_le.txt
@@ -448,3 +448,6 @@
 
 # CHECK: xori  $9,  $6, 17767
 0x67 0x45 0xc9 0x38
+
+# CHECK: synci 7500($19)
+0x4c 0x1d 0x7f 0x06
Index: test/MC/Mips/mips32r2/valid-xfail.s
===================================================================
--- test/MC/Mips/mips32r2/valid-xfail.s
+++ test/MC/Mips/mips32r2/valid-xfail.s
@@ -293,7 +293,6 @@
         swe             $24,94($k0)
         swle            $v1,-209($gp)
         swre            $k0,-202($s2)
-        synci           20023($s0)
         tlbginv
         tlbginvf
         tlbgp
Index: test/MC/Mips/mips32r2/valid.s
===================================================================
--- test/MC/Mips/mips32r2/valid.s
+++ test/MC/Mips/mips32r2/valid.s
@@ -233,3 +233,4 @@
         trunc.w.s $f28,$f30
         wsbh      $k1,$9
         xor       $s2,$a0,$s8
+        synci     -15842($a2)          # CHECK: synci -15842($6)        # encoding: [0x04,0xdf,0xc2,0x1e]
Index: test/MC/Mips/mips64r2/valid-xfail.s
===================================================================
--- test/MC/Mips/mips64r2/valid-xfail.s
+++ test/MC/Mips/mips64r2/valid-xfail.s
@@ -297,7 +297,6 @@
         swe $24,94($k0)
         swle            $v1,-209($gp)
         swre            $k0,-202($s2)
-        synci           20023($s0)
         tlbginv
         tlbginvf
         tlbgp