diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index 12dd1542d7994..7f2cab3eb11d6 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1,5 +1,5 @@
 #![cfg_attr(feature = "nightly", feature(step_trait, rustc_attrs, min_specialization))]
-#![cfg_attr(all(not(bootstrap), feature = "nightly"), allow(internal_features))]
+#![cfg_attr(feature = "nightly", allow(internal_features))]
 
 use std::fmt;
 #[cfg(feature = "nightly")]
diff --git a/compiler/rustc_arena/src/lib.rs b/compiler/rustc_arena/src/lib.rs
index e45b7c154faf2..f14463fe94029 100644
--- a/compiler/rustc_arena/src/lib.rs
+++ b/compiler/rustc_arena/src/lib.rs
@@ -24,7 +24,7 @@
 #![deny(unsafe_op_in_unsafe_fn)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 #![allow(clippy::mut_from_ref)] // Arena allocators are one of the places where this pattern is fine.
 
 use smallvec::SmallVec;
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index ef2788efbcfc5..3f544bf720989 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -11,7 +11,7 @@
 #![feature(trusted_step)]
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_data_structures/src/lib.rs b/compiler/rustc_data_structures/src/lib.rs
index 33772089744d1..bee5a89c4c737 100644
--- a/compiler/rustc_data_structures/src/lib.rs
+++ b/compiler/rustc_data_structures/src/lib.rs
@@ -37,7 +37,7 @@
 #![allow(rustc::potential_query_instability)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 #![deny(unsafe_op_in_unsafe_fn)]
 
 #[macro_use]
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index 3bf15505090cf..6c29144569d46 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -4,7 +4,7 @@
 #![feature(type_alias_impl_trait)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index 34518b53759d7..db5df554d23e6 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -15,7 +15,7 @@
 #![feature(box_patterns)]
 #![feature(error_reporter)]
 #![allow(incomplete_features)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_expand/src/lib.rs b/compiler/rustc_expand/src/lib.rs
index c4a9b2ace9a02..8b1fc5b90b43c 100644
--- a/compiler/rustc_expand/src/lib.rs
+++ b/compiler/rustc_expand/src/lib.rs
@@ -11,7 +11,7 @@
 #![feature(try_blocks)]
 #![recursion_limit = "256"]
 #![deny(rustc::untranslatable_diagnostic)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_hir/src/lib.rs b/compiler/rustc_hir/src/lib.rs
index 34214931a081d..094d5b1e77cf7 100644
--- a/compiler/rustc_hir/src/lib.rs
+++ b/compiler/rustc_hir/src/lib.rs
@@ -13,7 +13,7 @@
 #![recursion_limit = "256"]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_index/src/lib.rs b/compiler/rustc_index/src/lib.rs
index 9942c70c4ae71..c3de446a66e95 100644
--- a/compiler/rustc_index/src/lib.rs
+++ b/compiler/rustc_index/src/lib.rs
@@ -12,7 +12,7 @@
         test
     )
 )]
-#![cfg_attr(all(not(bootstrap), feature = "nightly"), allow(internal_features))]
+#![cfg_attr(feature = "nightly", allow(internal_features))]
 
 #[cfg(feature = "nightly")]
 pub mod bit_set;
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 585b10e79e484..e578f09b58fe1 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -40,7 +40,7 @@
 #![recursion_limit = "256"]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_macros/src/lib.rs b/compiler/rustc_macros/src/lib.rs
index f4593d0fe736d..85829906f4ef5 100644
--- a/compiler/rustc_macros/src/lib.rs
+++ b/compiler/rustc_macros/src/lib.rs
@@ -7,7 +7,7 @@
 #![allow(rustc::default_hash_types)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 #![recursion_limit = "128"]
 
 use synstructure::decl_derive;
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index d3fc1b2850eaa..50b69181d67ef 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -63,7 +63,7 @@
 #![feature(macro_metavar_expr)]
 #![recursion_limit = "512"]
 #![allow(rustc::potential_query_instability)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate bitflags;
diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
index 892be36aae770..598adbe798595 100644
--- a/compiler/rustc_parse/src/lib.rs
+++ b/compiler/rustc_parse/src/lib.rs
@@ -8,7 +8,7 @@
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![recursion_limit = "256"]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 53005ede84378..775870106b199 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -11,7 +11,7 @@
 #![allow(rustc::potential_query_instability, unused_parens)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_middle;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 76e54e60d142b..410705952bf98 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -18,7 +18,7 @@
 #![recursion_limit = "256"]
 #![allow(rustdoc::private_intra_doc_links)]
 #![allow(rustc::potential_query_instability)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate tracing;
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index a270817f3109b..d6c746a7bd85d 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -10,7 +10,7 @@
 #![allow(rustc::potential_query_instability)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index c24b8d9ec1709..efaed0f68cebd 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -23,7 +23,7 @@
 #![feature(round_char_boundary)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate rustc_macros;
diff --git a/compiler/rustc_target/src/lib.rs b/compiler/rustc_target/src/lib.rs
index b52002b123968..e838e11131f60 100644
--- a/compiler/rustc_target/src/lib.rs
+++ b/compiler/rustc_target/src/lib.rs
@@ -19,7 +19,7 @@
 #![feature(step_trait)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 use std::path::{Path, PathBuf};
 
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index b0f8ea7a05da5..e0abc7f04f575 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -6,7 +6,7 @@
 #![feature(unwrap_infallible)]
 #![deny(rustc::untranslatable_diagnostic)]
 #![deny(rustc::diagnostic_outside_of_impl)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[macro_use]
 extern crate bitflags;
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index efe8f5a8bcf3c..e43b6ac40391d 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -88,8 +88,8 @@
 #![warn(missing_docs)]
 #![allow(explicit_outlives_requirements)]
 #![warn(multiple_supertrait_upcastable)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
-#![cfg_attr(not(bootstrap), allow(rustdoc::redundant_explicit_links))]
+#![allow(internal_features)]
+#![allow(rustdoc::redundant_explicit_links)]
 //
 // Library features:
 // tidy-alphabetical-start
diff --git a/library/alloc/tests/vec.rs b/library/alloc/tests/vec.rs
index 183dd8e6e5932..9cb27899f1091 100644
--- a/library/alloc/tests/vec.rs
+++ b/library/alloc/tests/vec.rs
@@ -2499,7 +2499,6 @@ fn test_into_flattened_size_overflow() {
     let _ = v.into_flattened();
 }
 
-#[cfg(not(bootstrap))]
 #[test]
 fn test_box_zero_allocator() {
     use core::{alloc::AllocError, cell::RefCell};
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index bf4c682d33e5a..4bbe61ca3e772 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -1893,8 +1893,7 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 /// on an _exclusive_ `UnsafeCell<T>`. Even though `T` and `UnsafeCell<T>` have the
 /// same memory layout, the following is not allowed and undefined behavior:
 ///
-#[cfg_attr(bootstrap, doc = "```rust,no_run")]
-#[cfg_attr(not(bootstrap), doc = "```rust,compile_fail")]
+/// ```rust,compile_fail
 /// # use std::cell::UnsafeCell;
 /// unsafe fn not_allowed<T>(ptr: &UnsafeCell<T>) -> &mut T {
 ///   let t = ptr as *const UnsafeCell<T> as *mut T;
diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 676d4f2f38ca3..605870b8a7b9e 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -2399,7 +2399,6 @@ extern "rust-intrinsic" {
     /// that differs.  That allows optimizations that can read in large chunks.
     ///
     /// [valid]: crate::ptr#safety
-    #[cfg(not(bootstrap))]
     #[rustc_const_unstable(feature = "const_intrinsic_compare_bytes", issue = "none")]
     #[rustc_nounwind]
     pub fn compare_bytes(left: *const u8, right: *const u8, bytes: usize) -> i32;
@@ -2844,18 +2843,3 @@ pub const unsafe fn write_bytes<T>(dst: *mut T, val: u8, count: usize) {
         write_bytes(dst, val, count)
     }
 }
-
-/// Backfill for bootstrap
-#[cfg(bootstrap)]
-pub unsafe fn compare_bytes(left: *const u8, right: *const u8, bytes: usize) -> i32 {
-    extern "C" {
-        fn memcmp(s1: *const u8, s2: *const u8, n: usize) -> crate::ffi::c_int;
-    }
-
-    if bytes != 0 {
-        // SAFETY: Since bytes is non-zero, the caller has met `memcmp`'s requirements.
-        unsafe { memcmp(left, right, bytes).into() }
-    } else {
-        0
-    }
-}
diff --git a/library/core/src/intrinsics/mir.rs b/library/core/src/intrinsics/mir.rs
index ef0a2fd4ec4b3..b99346b6ba608 100644
--- a/library/core/src/intrinsics/mir.rs
+++ b/library/core/src/intrinsics/mir.rs
@@ -14,7 +14,7 @@
 //!
 //! ```rust
 //! #![feature(core_intrinsics, custom_mir)]
-#![cfg_attr(not(bootstrap), doc = "#![allow(internal_features)]")]
+//! #![allow(internal_features)]
 //!
 //! use core::intrinsics::mir::*;
 //!
@@ -64,7 +64,7 @@
 //!
 //! ```rust
 //! #![feature(core_intrinsics, custom_mir)]
-#![cfg_attr(not(bootstrap), doc = "#![allow(internal_features)]")]
+//! #![allow(internal_features)]
 //!
 //! use core::intrinsics::mir::*;
 //!
@@ -318,7 +318,7 @@ define!(
     /// # Examples
     ///
     /// ```rust
-    #[cfg_attr(not(bootstrap), doc = "#![allow(internal_features)]")]
+    /// #![allow(internal_features)]
     /// #![feature(custom_mir, core_intrinsics)]
     ///
     /// use core::intrinsics::mir::*;
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index a2729b3743cc2..f39c41764403f 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -96,9 +96,9 @@
 #![allow(explicit_outlives_requirements)]
 #![allow(incomplete_features)]
 #![warn(multiple_supertrait_upcastable)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 // Do not check link redundancy on bootstraping phase
-#![cfg_attr(not(bootstrap), allow(rustdoc::redundant_explicit_links))]
+#![allow(rustdoc::redundant_explicit_links)]
 //
 // Library features:
 // tidy-alphabetical-start
diff --git a/library/panic_abort/src/lib.rs b/library/panic_abort/src/lib.rs
index 76b3591965851..02534491da976 100644
--- a/library/panic_abort/src/lib.rs
+++ b/library/panic_abort/src/lib.rs
@@ -14,7 +14,7 @@
 #![feature(staged_api)]
 #![feature(rustc_attrs)]
 #![feature(c_unwind)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[cfg(target_os = "android")]
 mod android;
diff --git a/library/panic_unwind/src/lib.rs b/library/panic_unwind/src/lib.rs
index 009014de5c2c4..e7d34daa07962 100644
--- a/library/panic_unwind/src/lib.rs
+++ b/library/panic_unwind/src/lib.rs
@@ -19,14 +19,13 @@
 #![feature(panic_unwind)]
 #![feature(staged_api)]
 #![feature(std_internals)]
-#![cfg_attr(bootstrap, feature(abi_thiscall))]
 #![feature(rustc_attrs)]
 #![panic_runtime]
 #![feature(panic_runtime)]
 #![feature(c_unwind)]
 // `real_imp` is unused with Miri, so silence warnings.
 #![cfg_attr(miri, allow(dead_code))]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 use alloc::boxed::Box;
 use core::any::Any;
diff --git a/library/proc_macro/src/lib.rs b/library/proc_macro/src/lib.rs
index 83d637b685ac6..d382fec93521a 100644
--- a/library/proc_macro/src/lib.rs
+++ b/library/proc_macro/src/lib.rs
@@ -32,7 +32,7 @@
 #![feature(min_specialization)]
 #![feature(strict_provenance)]
 #![recursion_limit = "256"]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 #[unstable(feature = "proc_macro_internals", issue = "27812")]
 #[doc(hidden)]
diff --git a/library/profiler_builtins/src/lib.rs b/library/profiler_builtins/src/lib.rs
index a81d0a63547f8..ac685b18c2911 100644
--- a/library/profiler_builtins/src/lib.rs
+++ b/library/profiler_builtins/src/lib.rs
@@ -7,5 +7,5 @@
     issue = "none"
 )]
 #![allow(unused_features)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 #![feature(staged_api)]
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 58684ffe500ad..1955ef815ff80 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -220,10 +220,10 @@
 #![warn(missing_debug_implementations)]
 #![allow(explicit_outlives_requirements)]
 #![allow(unused_lifetimes)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 #![deny(rustc::existing_doc_keyword)]
 #![deny(fuzzy_provenance_casts)]
-#![cfg_attr(not(bootstrap), allow(rustdoc::redundant_explicit_links))]
+#![allow(rustdoc::redundant_explicit_links)]
 // Ensure that std can be linked against panic_abort despite compiled with `-C panic=unwind`
 #![deny(ffi_unwind_calls)]
 // std may use features in a platform-specific way
diff --git a/library/test/src/lib.rs b/library/test/src/lib.rs
index 64d10dd5712ab..413f0fba34224 100644
--- a/library/test/src/lib.rs
+++ b/library/test/src/lib.rs
@@ -21,7 +21,7 @@
 #![feature(process_exitcode_internals)]
 #![feature(panic_can_unwind)]
 #![feature(test)]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 // Public reexports
 pub use self::bench::{black_box, Bencher};
diff --git a/library/unwind/src/lib.rs b/library/unwind/src/lib.rs
index 0b4daeafe46df..62e97c65569f0 100644
--- a/library/unwind/src/lib.rs
+++ b/library/unwind/src/lib.rs
@@ -5,7 +5,7 @@
 #![feature(c_unwind)]
 #![feature(cfg_target_abi)]
 #![cfg_attr(not(target_env = "msvc"), feature(libc))]
-#![cfg_attr(not(bootstrap), allow(internal_features))]
+#![allow(internal_features)]
 
 cfg_if::cfg_if! {
     if #[cfg(target_env = "msvc")] {
diff --git a/src/tools/compiletest/src/runtest.rs b/src/tools/compiletest/src/runtest.rs
index 4ef79af3124a8..a2c828701e551 100644
--- a/src/tools/compiletest/src/runtest.rs
+++ b/src/tools/compiletest/src/runtest.rs
@@ -2354,14 +2354,7 @@ impl<'test> TestCx<'test> {
                 // Hide line numbers to reduce churn
                 rustc.arg("-Zui-testing");
                 rustc.arg("-Zdeduplicate-diagnostics=no");
-                // #[cfg(not(bootstrap)] unconditionally pass flag after beta bump
-                // since `ui-fulldeps --stage=1` builds using the stage 0 compiler,
-                // which doesn't have this flag.
-                if !(self.config.stage_id.starts_with("stage1-")
-                    && self.config.suite == "ui-fulldeps")
-                {
-                    rustc.arg("-Zwrite-long-types-to-disk=no");
-                }
+                rustc.arg("-Zwrite-long-types-to-disk=no");
                 // FIXME: use this for other modes too, for perf?
                 rustc.arg("-Cstrip=debuginfo");
             }
@@ -2483,13 +2476,8 @@ impl<'test> TestCx<'test> {
             rustc.args(&["-A", "unused"]);
         }
 
-        // #[cfg(not(bootstrap)] unconditionally pass flag after beta bump
-        // since `ui-fulldeps --stage=1` builds using the stage 0 compiler,
-        // which doesn't have this lint.
-        if !(self.config.stage_id.starts_with("stage1-") && self.config.suite == "ui-fulldeps") {
-            // Allow tests to use internal features.
-            rustc.args(&["-A", "internal_features"]);
-        }
+        // Allow tests to use internal features.
+        rustc.args(&["-A", "internal_features"]);
 
         if self.props.force_host {
             self.maybe_add_external_args(&mut rustc, &self.config.host_rustcflags);