diff --git a/src/librustc_feature/active.rs b/src/librustc_feature/active.rs
index d7c310a8b4c8b..35ef71def918e 100644
--- a/src/librustc_feature/active.rs
+++ b/src/librustc_feature/active.rs
@@ -579,6 +579,9 @@ declare_features! (
     /// Alloc calling `transmute` in const fn
     (active, const_fn_transmute, "1.46.0", Some(53605), None),
 
+    /// Instruction set declarations for functions (RFC 2867)
+    (active, isa_attribute, "1.47.0", Some(74727), None),
+
     // -------------------------------------------------------------------------
     // feature-group-end: actual feature gates
     // -------------------------------------------------------------------------
diff --git a/src/librustc_feature/builtin_attrs.rs b/src/librustc_feature/builtin_attrs.rs
index 879f06f89a70a..341740938b3cb 100644
--- a/src/librustc_feature/builtin_attrs.rs
+++ b/src/librustc_feature/builtin_attrs.rs
@@ -343,6 +343,11 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
         experimental!(register_tool),
     ),
 
+    // RFC 2867
+    gated!(
+        instruction_set, AssumedUsed, template!(List: "set"), experimental!(isa_attribute),
+    ),
+
     // ==========================================================================
     // Internal attributes: Stability, deprecation, and unsafe:
     // ==========================================================================
diff --git a/src/librustc_span/symbol.rs b/src/librustc_span/symbol.rs
index 98776a0478237..0bfae6f01d15f 100644
--- a/src/librustc_span/symbol.rs
+++ b/src/librustc_span/symbol.rs
@@ -590,11 +590,13 @@ symbols! {
         inlateout,
         inline,
         inout,
+        instruction_set,
         intel,
         into_iter,
         into_result,
         intrinsics,
         irrefutable_let_patterns,
+        isa_attribute,
         isize,
         issue,
         issue_5723_bootstrap,