diff --git a/lib/Target/ARM/ARMAddressingModes.h b/lib/Target/ARM/ARMAddressingModes.h
index 9e086ca..5be2fb2 100644
--- a/lib/Target/ARM/ARMAddressingModes.h
+++ b/lib/Target/ARM/ARMAddressingModes.h
@@ -463,20 +463,13 @@
   //    IB - Increment before
   //    DA - Decrement after
   //    DB - Decrement before
-  //
-  // If the 4th bit (writeback)is set, then the base register is updated after
-  // the memory transfer.
 
   static inline AMSubMode getAM4SubMode(unsigned Mode) {
     return (AMSubMode)(Mode & 0x7);
   }
 
-  static inline unsigned getAM4ModeImm(AMSubMode SubMode, bool WB = false) {
-    return (int)SubMode | ((int)WB << 3);
-  }
-
-  static inline bool getAM4WBFlag(unsigned Mode) {
-    return (Mode >> 3) & 1;
+  static inline unsigned getAM4ModeImm(AMSubMode SubMode) {
+    return (int)SubMode;
   }
 
   //===--------------------------------------------------------------------===//
diff --git a/lib/Target/ARM/ARMCodeEmitter.cpp b/lib/Target/ARM/ARMCodeEmitter.cpp
index 334c820..89f56e5 100644
--- a/lib/Target/ARM/ARMCodeEmitter.cpp
+++ b/lib/Target/ARM/ARMCodeEmitter.cpp
@@ -950,7 +950,7 @@
   Binary |= getAddrModeUPBits(ARM_AM::getAM4SubMode(MO.getImm()));
 
   // Set bit W(21)
-  if (ARM_AM::getAM4WBFlag(MO.getImm()))
+  if (IsUpdating)
     Binary |= 0x1 << ARMII::W_BitShift;
 
   // Set registers
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index 3fc37da..0547844 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -909,7 +909,7 @@
   def LDM_RET : AXI4ld<(outs GPR:$wb), (ins addrmode4:$addr, pred:$p,
                                         reglist:$dsts, variable_ops),
                        IndexModeUpd, LdStMulFrm, IIC_Br,
-                       "ldm${addr:submode}${p}\t$addr, $dsts",
+                       "ldm${addr:submode}${p}\t$addr!, $dsts",
                        "$addr.addr = $wb", []>;
 
 // On non-Darwin platforms R9 is callee-saved.
@@ -1354,7 +1354,7 @@
 def LDM_UPD : AXI4ld<(outs GPR:$wb), (ins addrmode4:$addr, pred:$p,
                                       reglist:$dsts, variable_ops),
                      IndexModeUpd, LdStMulFrm, IIC_iLoadm,
-                     "ldm${addr:submode}${p}\t$addr, $dsts",
+                     "ldm${addr:submode}${p}\t$addr!, $dsts",
                      "$addr.addr = $wb", []>;
 } // mayLoad, hasExtraDefRegAllocReq
 
@@ -1367,7 +1367,7 @@
 def STM_UPD : AXI4st<(outs GPR:$wb), (ins addrmode4:$addr, pred:$p,
                                       reglist:$srcs, variable_ops),
                      IndexModeUpd, LdStMulFrm, IIC_iStorem,
-                     "stm${addr:submode}${p}\t$addr, $srcs",
+                     "stm${addr:submode}${p}\t$addr!, $srcs",
                      "$addr.addr = $wb", []>;
 } // mayStore, hasExtraSrcRegAllocReq
 
diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td
index 37c9fc5..adf1adc 100644
--- a/lib/Target/ARM/ARMInstrThumb.td
+++ b/lib/Target/ARM/ARMInstrThumb.td
@@ -549,7 +549,7 @@
 def tLDM_UPD : T1It<(outs tGPR:$wb),
                     (ins addrmode4:$addr, pred:$p, reglist:$dsts, variable_ops),
                     IIC_iLoadm,
-                    "ldm${addr:submode}${p}\t$addr, $dsts",
+                    "ldm${addr:submode}${p}\t$addr!, $dsts",
                     "$addr.addr = $wb", []>,
                T1Encoding<{1,1,0,0,1,?}>; // A6.2 & A8.6.53
 } // mayLoad, hasExtraDefRegAllocReq
@@ -558,7 +558,7 @@
 def tSTM_UPD : T1It<(outs tGPR:$wb),
                     (ins addrmode4:$addr, pred:$p, reglist:$srcs, variable_ops),
                     IIC_iStorem,
-                    "stm${addr:submode}${p}\t$addr, $srcs",
+                    "stm${addr:submode}${p}\t$addr!, $srcs",
                     "$addr.addr = $wb", []>,
            T1Encoding<{1,1,0,0,0,?}>; // A6.2 & A8.6.189
 
diff --git a/lib/Target/ARM/ARMInstrThumb2.td b/lib/Target/ARM/ARMInstrThumb2.td
index ab9e926..262aae4 100644
--- a/lib/Target/ARM/ARMInstrThumb2.td
+++ b/lib/Target/ARM/ARMInstrThumb2.td
@@ -1218,7 +1218,7 @@
 
 def t2LDM_UPD : T2XIt<(outs GPR:$wb), (ins addrmode4:$addr, pred:$p,
                                        reglist:$dsts, variable_ops), IIC_iLoadm,
-                      "ldm${addr:submode}${p}${addr:wide}\t$addr, $dsts",
+                      "ldm${addr:submode}${p}${addr:wide}\t$addr!, $dsts",
                       "$addr.addr = $wb", []> {
   let Inst{31-27} = 0b11101;
   let Inst{26-25} = 0b00;
@@ -1244,7 +1244,7 @@
 def t2STM_UPD : T2XIt<(outs GPR:$wb), (ins addrmode4:$addr, pred:$p,
                                        reglist:$srcs, variable_ops),
                       IIC_iStorem,
-                      "stm${addr:submode}${p}${addr:wide}\t$addr, $srcs",
+                      "stm${addr:submode}${p}${addr:wide}\t$addr!, $srcs",
                       "$addr.addr = $wb", []> {
   let Inst{31-27} = 0b11101;
   let Inst{26-25} = 0b00;
diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index 8fbcf45..8bddf2d 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -505,7 +505,6 @@
       if (MI->getOperand(i).getReg() == Base)
         return false;
     }
-    assert(!ARM_AM::getAM4WBFlag(MI->getOperand(1).getImm()));
     Mode = ARM_AM::getAM4SubMode(MI->getOperand(1).getImm());
   } else {
     // VLDM{D|S}, VSTM{D|S} addressing mode 5 ops.
@@ -573,7 +572,7 @@
     .addReg(Base, getKillRegState(BaseKill));
   if (isAM4) {
     // [t2]LDM_UPD, [t2]STM_UPD
-    MIB.addImm(ARM_AM::getAM4ModeImm(Mode, true))
+    MIB.addImm(ARM_AM::getAM4ModeImm(Mode))
       .addImm(Pred).addReg(PredReg);
   } else {
     // VLDM[SD}_UPD, VSTM[SD]_UPD
diff --git a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
index 32d724d..3c27913 100644
--- a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
@@ -524,8 +524,6 @@
       O << ".w";
   } else {
     printOperand(MI, Op);
-    if (ARM_AM::getAM4WBFlag(MO2.getImm()))
-      O << "!";
   }
 }
 
diff --git a/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp b/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
index 7950adb..66abf99 100644
--- a/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
+++ b/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
@@ -232,8 +232,6 @@
       O << ".w";
   } else {
     printOperand(MI, OpNum);
-    if (ARM_AM::getAM4WBFlag(MO2.getImm()))
-      O << "!";
   }
 }