diff --git a/library/stdarch/src/x86/sse41.rs b/library/stdarch/src/x86/sse41.rs
index 6433cd35f4a1..885f83a8baf3 100644
--- a/library/stdarch/src/x86/sse41.rs
+++ b/library/stdarch/src/x86/sse41.rs
@@ -287,6 +287,24 @@ pub unsafe fn _mm_cvtepi8_epi64(a: i8x16) -> i64x2 {
 }
 */
 
+/// Sign extend packed 16-bit integers in `a` to packed 32-bit integers
+#[inline(always)]
+#[target_feature = "+sse4.1"]
+#[cfg_attr(test, assert_instr(pmovsxwd))]
+pub unsafe fn _mm_cvtepi16_epi32(a: i16x8) -> i32x4 {
+    simd_cast::<::v64::i16x4, _>(simd_shuffle4(a, a, [0, 1, 2, 3]))
+}
+
+/// Sign extend packed 16-bit integers in a to packed 64-bit integers
+/*
+#[inline(always)]
+#[target_feature = "+sse4.1"]
+#[cfg_attr(test, assert_instr(pmovsxwq))]
+pub unsafe fn _mm_cvtepi16_epi64(a: i16x8) -> i64x2 {
+    simd_cast::<::v32::i16x2, _>(simd_shuffle2(a, a, [0, 1]))
+}
+*/
+
 /// Returns the dot product of two f64x2 vectors.
 ///
 /// `imm8[1:0]` is the broadcast mask, and `imm8[5:4]` is the condition mask.
@@ -825,6 +843,31 @@ mod tests {
     }
     */
 
+    #[simd_test = "sse4.1"]
+    unsafe fn _mm_cvtepi16_epi32() {
+        let a = i16x8::splat(10);
+        let r = sse41::_mm_cvtepi16_epi32(a);
+        let e = i32x4::splat(10);
+        assert_eq!(r, e);
+        let a =  i16x8::splat(-10);
+        let r = sse41::_mm_cvtepi16_epi32(a);
+        let e = i32x4::splat(-10);
+        assert_eq!(r, e);
+    }
+
+/*
+    #[simd_test = "sse4.1"]
+    unsafe fn _mm_cvtepi16_epi64() {
+        let a = i16x8::splat(10);
+        let r = sse41::_mm_cvtepi16_epi64(a);
+        let e = i64x2::splat(10);
+        assert_eq!(r, e);
+        let a =  i16x8::splat(-10);
+        let r = sse41::_mm_cvtepi16_epi64(a);
+        let e = i64x2::splat(-10);
+        assert_eq!(r, e);
+    }
+*/
     #[simd_test = "sse4.1"]
     unsafe fn _mm_dp_pd() {
         let a = f64x2::new(2.0, 3.0);