diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index 93739722cc44d0ad51f500beac5959dc14b2c9a0..c08c363c04f8db5a4189f4aa6462dcdec52df3c3 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -258,10 +258,16 @@ def so_imm_neg :
     return ARM_AM::getSOImmVal(-(uint32_t)N->getZExtValue()) != -1;
   }], so_imm_neg_XFORM>;
 
+// Note: this pattern doesn't require an encoder method and such, as it's
+// only used on aliases (Pat<> and InstAlias<>). The actual encoding
+// is handled by the destination instructions, which use t2_so_imm.
+def so_imm_not_asmoperand : AsmOperandClass { let Name = "ARMSOImmNot"; }
 def so_imm_not :
-  PatLeaf<(imm), [{
+  Operand<i32>, PatLeaf<(imm), [{
     return ARM_AM::getSOImmVal(~(uint32_t)N->getZExtValue()) != -1;
-  }], so_imm_not_XFORM>;
+  }], so_imm_not_XFORM> {
+  let ParserMatchClass = so_imm_not_asmoperand;
+}
 
 // sext_16_node predicate - True if the SDNode is sign-extended 16 or more bits.
 def sext_16_node : PatLeaf<(i32 GPR:$a), [{
@@ -4988,3 +4994,9 @@ def : MnemonicAlias<"usubaddx", "usax">;
 //                (LDRHTi GPR:$Rt, GPR:$Rt, addr_offset_none:$addr, 0, pred:$p)>;
 //def : InstAlias<"ldrsht${p} $Rt, $addr",
 //                (LDRSHTi GPR:$Rt, GPR:$Rt, addr_offset_none:$addr, 0, pred:$p)>;
+
+
+// "mov Rd, so_imm_not" can be handled via "mvn" in assembly, just like
+// for isel.
+def : ARMInstAlias<"mov${s}${p} $Rd, $imm",
+                   (MVNi rGPR:$Rd, so_imm_not:$imm, pred:$p, cc_out:$s)>;
diff --git a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index ad5f061eabae6931b44ba0224daca0255b6c98fb..03fba5aee98390bffd05ba24c2aca7e0d65eece6 100644
--- a/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -657,6 +657,14 @@ public:
     int64_t Value = CE->getValue();
     return ARM_AM::getSOImmVal(Value) != -1;
   }
+  bool isARMSOImmNot() const {
+    if (Kind != k_Immediate)
+      return false;
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    if (!CE) return false;
+    int64_t Value = CE->getValue();
+    return ARM_AM::getSOImmVal(~Value) != -1;
+  }
   bool isT2SOImm() const {
     if (Kind != k_Immediate)
       return false;
@@ -1257,6 +1265,14 @@ public:
     Inst.addOperand(MCOperand::CreateImm(~CE->getValue()));
   }
 
+  void addARMSOImmNotOperands(MCInst &Inst, unsigned N) const {
+    assert(N == 1 && "Invalid number of operands!");
+    // The operand is actually a so_imm, but we have its bitwise
+    // negation in the assembly source, so twiddle it here.
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
+    Inst.addOperand(MCOperand::CreateImm(~CE->getValue()));
+  }
+
   void addSetEndImmOperands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     addExpr(Inst, getImm());