diff --git a/src/codegen/x64/assembler-x64.cc b/src/codegen/x64/assembler-x64.cc
index 95319c3ced..108f381ba7 100644
--- a/src/codegen/x64/assembler-x64.cc
+++ b/src/codegen/x64/assembler-x64.cc
@@ -3347,26 +3347,6 @@ void Assembler::cvtqsi2sd(XMMRegister dst, Register src) {
   emit_sse_operand(dst, src);
 }
 
-void Assembler::cvtss2sd(XMMRegister dst, XMMRegister src) {
-  DCHECK(!IsEnabled(AVX));
-  EnsureSpace ensure_space(this);
-  emit(0xF3);
-  emit_optional_rex_32(dst, src);
-  emit(0x0F);
-  emit(0x5A);
-  emit_sse_operand(dst, src);
-}
-
-void Assembler::cvtss2sd(XMMRegister dst, Operand src) {
-  DCHECK(!IsEnabled(AVX));
-  EnsureSpace ensure_space(this);
-  emit(0xF3);
-  emit_optional_rex_32(dst, src);
-  emit(0x0F);
-  emit(0x5A);
-  emit_sse_operand(dst, src);
-}
-
 void Assembler::cvtsd2si(Register dst, XMMRegister src) {
   DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
diff --git a/src/codegen/x64/assembler-x64.h b/src/codegen/x64/assembler-x64.h
index 3c0d20879b..cd93c7f856 100644
--- a/src/codegen/x64/assembler-x64.h
+++ b/src/codegen/x64/assembler-x64.h
@@ -1242,9 +1242,6 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
   void cvtqsi2sd(XMMRegister dst, Operand src);
   void cvtqsi2sd(XMMRegister dst, Register src);
 
-  void cvtss2sd(XMMRegister dst, XMMRegister src);
-  void cvtss2sd(XMMRegister dst, Operand src);
-
   void cvtsd2si(Register dst, XMMRegister src);
   void cvtsd2siq(Register dst, XMMRegister src);
 
@@ -1438,12 +1435,6 @@ class V8_EXPORT_PRIVATE Assembler : public AssemblerBase {
   void vcvtdq2pd(XMMRegister dst, XMMRegister src) {
     vinstr(0xe6, dst, xmm0, src, kF3, k0F, kWIG);
   }
-  void vcvtss2sd(XMMRegister dst, XMMRegister src1, XMMRegister src2) {
-    vinstr(0x5a, dst, src1, src2, kF3, k0F, kWIG);
-  }
-  void vcvtss2sd(XMMRegister dst, XMMRegister src1, Operand src2) {
-    vinstr(0x5a, dst, src1, src2, kF3, k0F, kWIG);
-  }
   void vcvttps2dq(XMMRegister dst, XMMRegister src) {
     vinstr(0x5b, dst, xmm0, src, kF3, k0F, kWIG);
   }
diff --git a/src/codegen/x64/sse-instr.h b/src/codegen/x64/sse-instr.h
index 452cc0f690..d1223b69a1 100644
--- a/src/codegen/x64/sse-instr.h
+++ b/src/codegen/x64/sse-instr.h
@@ -32,6 +32,7 @@
   V(sqrtss, F3, 0F, 51)            \
   V(addss, F3, 0F, 58)             \
   V(mulss, F3, 0F, 59)             \
+  V(cvtss2sd, F3, 0F, 5A)          \
   V(subss, F3, 0F, 5C)             \
   V(minss, F3, 0F, 5D)             \
   V(divss, F3, 0F, 5E)             \