Index: llvm/trunk/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -1849,6 +1849,20 @@
   case AArch64::BFMWri:
   case AArch64::BFMXri:
     return getUsefulBitsFromBFM(SDValue(UserNode, 0), Orig, UsefulBits, Depth);
+
+  case AArch64::STRBui:
+  case AArch64::STRBBui:
+    if (UserNode->getOperand(0) != Orig)
+      return;
+    UsefulBits &= APInt(UsefulBits.getBitWidth(), 0xff);
+    return;
+
+  case AArch64::STRHui:
+  case AArch64::STRHHui:
+    if (UserNode->getOperand(0) != Orig)
+      return;
+    UsefulBits &= APInt(UsefulBits.getBitWidth(), 0xffff);
+    return;
   }
 }
 
Index: llvm/trunk/test/CodeGen/AArch64/bitfield-insert.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/bitfield-insert.ll
+++ llvm/trunk/test/CodeGen/AArch64/bitfield-insert.ll
@@ -237,3 +237,39 @@
   %shl.4 = shl i32 %or.3, 8     ;   A A A 0
   ret i32 %shl.4
 }
+
+define void @test_nouseful_strb(i32* %ptr32, i8* %ptr8, i32 %x)  {
+entry:
+; CHECK-LABEL: @test_nouseful_strb
+; CHECK: ldr [[REG1:w[0-9]+]],
+; CHECK-NOT:  and {{w[0-9]+}}, {{w[0-9]+}}, #0xf8
+; CHECK-NEXT: bfxil [[REG1]], w2, #16, #3
+; CHECK-NEXT: strb [[REG1]],
+; CHECK-NEXT: ret
+  %0 = load i32, i32* %ptr32, align 8
+  %and = and i32 %0, -8
+  %shr = lshr i32 %x, 16
+  %and1 = and i32 %shr, 7
+  %or = or i32 %and, %and1
+  %trunc = trunc i32 %or to i8
+  store i8 %trunc, i8* %ptr8
+  ret void
+}
+
+define void @test_nouseful_strh(i32* %ptr32, i16* %ptr16, i32 %x)  {
+entry:
+; CHECK-LABEL: @test_nouseful_strh
+; CHECK: ldr [[REG1:w[0-9]+]],
+; CHECK-NOT:  and {{w[0-9]+}}, {{w[0-9]+}}, #0xfff0
+; CHECK-NEXT: bfxil [[REG1]], w2, #16, #4
+; CHECK-NEXT: strh [[REG1]],
+; CHECK-NEXT: ret
+  %0 = load i32, i32* %ptr32, align 8
+  %and = and i32 %0, -16
+  %shr = lshr i32 %x, 16
+  %and1 = and i32 %shr, 15
+  %or = or i32 %and, %and1
+  %trunc = trunc i32 %or to i16
+  store i16 %trunc, i16* %ptr16
+  ret void
+}