diff --git a/src/bootstrap/bin/rustc.rs b/src/bootstrap/bin/rustc.rs
index 9c01de8aa8251..d7887f74cc1c0 100644
--- a/src/bootstrap/bin/rustc.rs
+++ b/src/bootstrap/bin/rustc.rs
@@ -102,8 +102,13 @@ fn main() {
     // FIXME: the fact that core here is excluded is due to core_arch from our stdarch submodule
     // being broken on the beta compiler with bootstrap passed, so this is a temporary workaround
     // (we've just snapped, so there are no cfg(bootstrap) related annotations in core).
-    if stage == "0" && crate_name != Some("core") {
-        cmd.arg("--cfg").arg("bootstrap");
+    if stage == "0" {
+        if crate_name != Some("core") {
+            cmd.arg("--cfg").arg("bootstrap");
+        } else {
+            // NOTE(eddyb) see FIXME above, except now we need annotations again in core.
+            cmd.arg("--cfg").arg("boostrap_stdarch_ignore_this");
+        }
     }
 
     // Print backtrace in case of ICE
diff --git a/src/libcore/intrinsics.rs b/src/libcore/intrinsics.rs
index 995ee56440ea5..d145f2212f93a 100644
--- a/src/libcore/intrinsics.rs
+++ b/src/libcore/intrinsics.rs
@@ -1293,38 +1293,38 @@ extern "rust-intrinsic" {
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_add` method. For example,
     /// [`std::u32::wrapping_add`](../../std/primitive.u32.html#method.wrapping_add)
-    #[cfg(bootstrap)]
+    #[cfg(boostrap_stdarch_ignore_this)]
     pub fn overflowing_add<T>(a: T, b: T) -> T;
     /// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits.
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_sub` method. For example,
     /// [`std::u32::wrapping_sub`](../../std/primitive.u32.html#method.wrapping_sub)
-    #[cfg(bootstrap)]
+    #[cfg(boostrap_stdarch_ignore_this)]
     pub fn overflowing_sub<T>(a: T, b: T) -> T;
     /// Returns (a * b) mod 2<sup>N</sup>, where N is the width of T in bits.
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_mul` method. For example,
     /// [`std::u32::wrapping_mul`](../../std/primitive.u32.html#method.wrapping_mul)
-    #[cfg(bootstrap)]
+    #[cfg(boostrap_stdarch_ignore_this)]
     pub fn overflowing_mul<T>(a: T, b: T) -> T;
 
     /// Returns (a + b) mod 2<sup>N</sup>, where N is the width of T in bits.
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_add` method. For example,
     /// [`std::u32::wrapping_add`](../../std/primitive.u32.html#method.wrapping_add)
-    #[cfg(not(bootstrap))]
+    #[cfg(not(boostrap_stdarch_ignore_this))]
     pub fn wrapping_add<T>(a: T, b: T) -> T;
     /// Returns (a - b) mod 2<sup>N</sup>, where N is the width of T in bits.
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_sub` method. For example,
     /// [`std::u32::wrapping_sub`](../../std/primitive.u32.html#method.wrapping_sub)
-    #[cfg(not(bootstrap))]
+    #[cfg(not(boostrap_stdarch_ignore_this))]
     pub fn wrapping_sub<T>(a: T, b: T) -> T;
     /// Returns (a * b) mod 2<sup>N</sup>, where N is the width of T in bits.
     /// The stabilized versions of this intrinsic are available on the integer
     /// primitives via the `wrapping_mul` method. For example,
     /// [`std::u32::wrapping_mul`](../../std/primitive.u32.html#method.wrapping_mul)
-    #[cfg(not(bootstrap))]
+    #[cfg(not(boostrap_stdarch_ignore_this))]
     pub fn wrapping_mul<T>(a: T, b: T) -> T;
 
     /// Computes `a + b`, while saturating at numeric bounds.
diff --git a/src/libcore/num/mod.rs b/src/libcore/num/mod.rs
index f82d94153e846..b46e06f8d8ada 100644
--- a/src/libcore/num/mod.rs
+++ b/src/libcore/num/mod.rs
@@ -1112,11 +1112,11 @@ $EndFeature, "
                           without modifying the original"]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
-                #[cfg(bootstrap)] {
+                #[cfg(boostrap_stdarch_ignore_this)] {
                     intrinsics::overflowing_add(self, rhs)
                 }
 
-                #[cfg(not(bootstrap))] {
+                #[cfg(not(boostrap_stdarch_ignore_this))] {
                     intrinsics::wrapping_add(self, rhs)
                 }
             }
@@ -1141,11 +1141,11 @@ $EndFeature, "
                           without modifying the original"]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
-                #[cfg(bootstrap)] {
+                #[cfg(boostrap_stdarch_ignore_this)] {
                     intrinsics::overflowing_sub(self, rhs)
                 }
 
-                #[cfg(not(bootstrap))] {
+                #[cfg(not(boostrap_stdarch_ignore_this))] {
                     intrinsics::wrapping_sub(self, rhs)
                 }
             }
@@ -1169,11 +1169,11 @@ $EndFeature, "
                           without modifying the original"]
             #[inline]
             pub const fn wrapping_mul(self, rhs: Self) -> Self {
-                #[cfg(bootstrap)] {
+                #[cfg(boostrap_stdarch_ignore_this)] {
                     intrinsics::overflowing_mul(self, rhs)
                 }
 
-                #[cfg(not(bootstrap))] {
+                #[cfg(not(boostrap_stdarch_ignore_this))] {
                     intrinsics::wrapping_mul(self, rhs)
                 }
             }
@@ -3049,11 +3049,11 @@ $EndFeature, "
                           without modifying the original"]
             #[inline]
             pub const fn wrapping_add(self, rhs: Self) -> Self {
-                #[cfg(bootstrap)] {
+                #[cfg(boostrap_stdarch_ignore_this)] {
                     intrinsics::overflowing_add(self, rhs)
                 }
 
-                #[cfg(not(bootstrap))] {
+                #[cfg(not(boostrap_stdarch_ignore_this))] {
                     intrinsics::wrapping_add(self, rhs)
                 }
             }
@@ -3077,11 +3077,11 @@ $EndFeature, "
                           without modifying the original"]
             #[inline]
             pub const fn wrapping_sub(self, rhs: Self) -> Self {
-                #[cfg(bootstrap)] {
+                #[cfg(boostrap_stdarch_ignore_this)] {
                     intrinsics::overflowing_sub(self, rhs)
                 }
 
-                #[cfg(not(bootstrap))] {
+                #[cfg(not(boostrap_stdarch_ignore_this))] {
                     intrinsics::wrapping_sub(self, rhs)
                 }
             }
@@ -3106,11 +3106,11 @@ $EndFeature, "
                           without modifying the original"]
         #[inline]
         pub const fn wrapping_mul(self, rhs: Self) -> Self {
-            #[cfg(bootstrap)] {
+            #[cfg(boostrap_stdarch_ignore_this)] {
                 intrinsics::overflowing_mul(self, rhs)
             }
 
-            #[cfg(not(bootstrap))] {
+            #[cfg(not(boostrap_stdarch_ignore_this))] {
                 intrinsics::wrapping_mul(self, rhs)
             }
         }