diff --git a/src/backend_x64/emit_x64.cpp b/src/backend_x64/emit_x64.cpp
index d26ea9fd..06659820 100644
--- a/src/backend_x64/emit_x64.cpp
+++ b/src/backend_x64/emit_x64.cpp
@@ -1275,26 +1275,6 @@ void EmitX64::EmitCountLeadingZeros(IR::Block&, IR::Inst* inst) {
     }
 }
 
-void EmitX64::EmitNegateLowWord(IR::Block&, IR::Inst* inst) {
-    IR::Value a = inst->GetArg(0);
-
-    Xbyak::Reg32 result = reg_alloc.UseDefGpr(a, inst).cvt32();
-
-    code->ror(result, 16);
-    code->xor(result, 0xFFFF0000);
-    code->add(result, 0x00010000);
-    code->ror(result, 16);
-}
-
-void EmitX64::EmitNegateHighWord(IR::Block&, IR::Inst* inst) {
-    IR::Value a = inst->GetArg(0);
-
-    Xbyak::Reg32 result = reg_alloc.UseDefGpr(a, inst).cvt32();
-
-    code->xor(result, 0xFFFF0000);
-    code->add(result, 0x00010000);
-}
-
 void EmitX64::EmitSignedSaturatedAdd(IR::Block& block, IR::Inst* inst) {
     auto overflow_inst = inst->GetAssociatedPseudoOperation(IR::Opcode::GetOverflowFromOp);
 
diff --git a/src/frontend/ir/ir_emitter.cpp b/src/frontend/ir/ir_emitter.cpp
index 77010eeb..9d7795cb 100644
--- a/src/frontend/ir/ir_emitter.cpp
+++ b/src/frontend/ir/ir_emitter.cpp
@@ -328,14 +328,6 @@ Value IREmitter::CountLeadingZeros(const Value& a) {
     return Inst(Opcode::CountLeadingZeros, {a});
 }
 
-Value IREmitter::NegateLowWord(const Value& a) {
-    return Inst(Opcode::NegateLowWord, {a});
-}
-
-Value IREmitter::NegateHighWord(const Value& a) {
-    return Inst(Opcode::NegateHighWord, {a});
-}
-
 IREmitter::ResultAndOverflow IREmitter::SignedSaturatedAdd(const Value& a, const Value& b) {
     auto result = Inst(Opcode::SignedSaturatedAdd, {a, b});
     auto overflow = Inst(Opcode::GetOverflowFromOp, {result});
diff --git a/src/frontend/ir/ir_emitter.h b/src/frontend/ir/ir_emitter.h
index f1928955..250137f6 100644
--- a/src/frontend/ir/ir_emitter.h
+++ b/src/frontend/ir/ir_emitter.h
@@ -133,8 +133,6 @@ public:
     Value ByteReverseHalf(const Value& a);
     Value ByteReverseDual(const Value& a);
     Value CountLeadingZeros(const Value& a);
-    Value NegateLowWord(const Value& a);
-    Value NegateHighWord(const Value& a);
 
     ResultAndOverflow SignedSaturatedAdd(const Value& a, const Value& b);
     ResultAndOverflow SignedSaturatedSub(const Value& a, const Value& b);
diff --git a/src/frontend/ir/opcodes.inc b/src/frontend/ir/opcodes.inc
index 5d8e8bc7..907e07d0 100644
--- a/src/frontend/ir/opcodes.inc
+++ b/src/frontend/ir/opcodes.inc
@@ -73,8 +73,6 @@ OPCODE(ByteReverseWord,         T::U32,         T::U32
 OPCODE(ByteReverseHalf,         T::U16,         T::U16                                          )
 OPCODE(ByteReverseDual,         T::U64,         T::U64                                          )
 OPCODE(CountLeadingZeros,       T::U32,         T::U32                                          )
-OPCODE(NegateLowWord,           T::U32,         T::U32                                          )
-OPCODE(NegateHighWord,          T::U32,         T::U32                                          )
 
 // Saturated instructions
 OPCODE(SignedSaturatedAdd,      T::U32,         T::U32,         T::U32                          )