diff --git a/lib/Target/ARM/ARMInstrFormats.td b/lib/Target/ARM/ARMInstrFormats.td
index 7cbc9111dec..43f11948974 100644
--- a/lib/Target/ARM/ARMInstrFormats.td
+++ b/lib/Target/ARM/ARMInstrFormats.td
@@ -481,6 +481,8 @@ class AIswp<bit b, dag oops, dag iops, string opc, list<dag> pattern>
   let Inst{15-12} = Rt;
   let Inst{11-4} = 0b00001001;
   let Inst{3-0} = Rt2;
+
+  let DecoderMethod = "DecodeSwap";
 }
 
 // addrmode1 instructions
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index b9cbc83f217..93739722cc4 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -1640,7 +1640,7 @@ class CPS<dag iops, string asm_ops>
   let Inst{27-20} = 0b00010000;
   let Inst{19-18} = imod;
   let Inst{17}    = M; // Enabled if mode is set;
-  let Inst{16}    = 0;
+  let Inst{16-9}  = 0b00000000;
   let Inst{8-6}   = iflags;
   let Inst{5}     = 0;
   let Inst{4-0}   = mode;
diff --git a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index 0e63d9cc24d..92a4cdca517 100644
--- a/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -249,6 +249,8 @@ static DecodeStatus DecodeVMOVSRR(llvm::MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder);
 static DecodeStatus DecodeVMOVRRS(llvm::MCInst &Inst, unsigned Insn,
                                uint64_t Address, const void *Decoder);
+static DecodeStatus DecodeSwap(llvm::MCInst &Inst, unsigned Insn,
+                               uint64_t Address, const void *Decoder);
 
 static DecodeStatus DecodeThumbAddSpecialReg(llvm::MCInst &Inst, uint16_t Insn,
                                uint64_t Address, const void *Decoder);
@@ -4043,3 +4045,25 @@ static DecodeStatus DecodeT2ShifterImmOperand(llvm::MCInst &Inst, uint32_t Val,
   return S;
 }
 
+static DecodeStatus DecodeSwap(llvm::MCInst &Inst, unsigned Insn,
+                               uint64_t Address, const void *Decoder) {
+  unsigned Rt   = fieldFromInstruction32(Insn, 12, 4);
+  unsigned Rt2  = fieldFromInstruction32(Insn, 0,  4);
+  unsigned Rn   = fieldFromInstruction32(Insn, 16, 4);
+  unsigned pred = fieldFromInstruction32(Insn, 28, 4);
+
+  if (pred == 0xF)
+    return DecodeCPSInstruction(Inst, Insn, Address, Decoder);
+
+  DecodeStatus S = MCDisassembler::Success;
+  if (!Check(S, DecodeGPRnopcRegisterClass(Inst, Rt, Address, Decoder)))
+    return MCDisassembler::Fail;
+  if (!Check(S, DecodeGPRnopcRegisterClass(Inst, Rt2, Address, Decoder)))
+    return MCDisassembler::Fail;
+  if (!Check(S, DecodeGPRnopcRegisterClass(Inst, Rn, Address, Decoder)))
+    return MCDisassembler::Fail;
+  if (!Check(S, DecodePredicateOperand(Inst, pred, Address, Decoder)))
+    return MCDisassembler::Fail;
+
+  return S;
+}
diff --git a/test/MC/Disassembler/ARM/invalid-CPS3p-arm.txt b/test/MC/Disassembler/ARM/invalid-CPS3p-arm.txt
index 6fdb55e691d..8146b5cb446 100644
--- a/test/MC/Disassembler/ARM/invalid-CPS3p-arm.txt
+++ b/test/MC/Disassembler/ARM/invalid-CPS3p-arm.txt
@@ -1,4 +1,4 @@
 # RUN: llvm-mc --disassemble %s -triple=arm-apple-darwin9 |& grep {potentially undefined instruction encoding}
 
 # invalid (imod, M, iflags) combination
-0x93 0x1c 0x02 0xf1
+0x93 0x00 0x02 0xf1