diff --git a/library/stdarch/crates/core_arch/src/simd.rs b/library/stdarch/crates/core_arch/src/simd.rs
index 5c8425623d61..f6b2babf09d2 100644
--- a/library/stdarch/crates/core_arch/src/simd.rs
+++ b/library/stdarch/crates/core_arch/src/simd.rs
@@ -191,3 +191,7 @@ simd_ty!(i32x16[i32]:
          i32, i32, i32, i32, i32, i32, i32, i32
          | x0, x1, x2, x3, x4, x5, x6, x7,
          x8, x9, x10, x11, x12, x13, x14, x15);
+
+simd_ty!(i64x8[i64]:
+         i64, i64, i64, i64, i64, i64, i64, i64
+         | x0, x1, x2, x3, x4, x5, x6, x7);
diff --git a/library/stdarch/crates/core_arch/src/x86/avx512f.rs b/library/stdarch/crates/core_arch/src/x86/avx512f.rs
index 1322f3266206..166ca179a52a 100644
--- a/library/stdarch/crates/core_arch/src/x86/avx512f.rs
+++ b/library/stdarch/crates/core_arch/src/x86/avx512f.rs
@@ -87,6 +87,13 @@ pub unsafe fn _mm512_setr_epi32(
     mem::transmute(r)
 }
 
+/// Broadcast 64-bit integer `a` to all elements of `dst`.
+#[inline]
+#[target_feature(enable = "avx512f")]
+pub unsafe fn _mm512_set1_epi64(a: i64) -> __m512i {
+    mem::transmute(i64x8::splat(a))
+}
+
 #[cfg(test)]
 mod tests {
     use std;