diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 190f0fe3cddcf..d95c79254966b 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -137,6 +137,16 @@ impl Step for Std {
         let target = self.target;
         let compiler = self.compiler;
 
+        // We already have std ready to be used for stage 0.
+        if compiler.stage == 0 && !builder.config.build_std_on_stage0 {
+            builder.ensure(StdLink::from_std(
+                self,
+                builder.compiler(compiler.stage, builder.config.build),
+            ));
+
+            return;
+        }
+
         // When using `download-rustc`, we already have artifacts for the host available. Don't
         // recompile them.
         if builder.download_rustc() && target == builder.build.build
@@ -175,8 +185,20 @@ impl Step for Std {
 
         let mut target_deps = builder.ensure(StartupObjects { compiler, target });
 
-        let compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
-        if compiler_to_use != compiler {
+        let mut compiler_to_use = builder.compiler_for(compiler.stage, compiler.host, target);
+
+        // We only need to build std twice; therefore,
+        // - If stage 2 std is built, the artifacts are fully up to date. For the next stages, uplift the artifacts instead of compiling std again.
+        // - If `--build-std-on-stage0` was used it means std was already built on stage 0. So, if stage 1 is built, that means std is fully up to date.
+        //      For the next stages, uplift the artifacts instead of compiling std again.
+        if (compiler.stage > 2 || builder.config.build_std_on_stage0) && compiler_to_use != compiler
+        {
+            // If stage 2 std was built (not uplifted), uplift the artifacts from stage 2.
+            // (This is necessary; without this, they will be uplifted from stage 1).
+            if !builder.config.build_std_on_stage0 && compiler.stage > 2 {
+                compiler_to_use.stage = 2;
+            }
+
             builder.ensure(Std::new(compiler_to_use, target));
             let msg = if compiler_to_use.host == target {
                 format!(
@@ -585,18 +607,16 @@ impl Step for StdLink {
             (libdir, hostdir)
         };
 
-        add_to_sysroot(builder, &libdir, &hostdir, &libstd_stamp(builder, compiler, target));
+        let is_downloaded_beta_stage0 = builder
+            .build
+            .config
+            .initial_rustc
+            .starts_with(builder.out.join(&compiler.host.triple).join("stage0/bin"));
 
         // Special case for stage0, to make `rustup toolchain link` and `x dist --stage 0`
         // work for stage0-sysroot. We only do this if the stage0 compiler comes from beta,
         // and is not set to a custom path.
-        if compiler.stage == 0
-            && builder
-                .build
-                .config
-                .initial_rustc
-                .starts_with(builder.out.join(&compiler.host.triple).join("stage0/bin"))
-        {
+        if compiler.stage == 0 && is_downloaded_beta_stage0 && !builder.config.build_std_on_stage0 {
             // Copy bin files from stage0/bin to stage0-sysroot/bin
             let sysroot = builder.out.join(&compiler.host.triple).join("stage0-sysroot");
 
@@ -608,7 +628,10 @@ impl Step for StdLink {
 
             // Copy all *.so files from stage0/lib to stage0-sysroot/lib
             let stage0_lib_dir = builder.out.join(&host).join("stage0/lib");
-            if let Ok(files) = fs::read_dir(&stage0_lib_dir) {
+
+            if !builder.config.build_std_on_stage0 {
+                builder.cp_r(&stage0_lib_dir, &sysroot.join("lib"));
+            } else if let Ok(files) = fs::read_dir(&stage0_lib_dir) {
                 for file in files {
                     let file = t!(file);
                     let path = file.path();
@@ -630,6 +653,11 @@ impl Step for StdLink {
             if stage0_codegen_backends.exists() {
                 builder.cp_r(&stage0_codegen_backends, &sysroot_codegen_backends);
             }
+        } else if compiler.stage == 0 && !builder.config.build_std_on_stage0 {
+            let sysroot = builder.out.join(&compiler.host.triple).join("stage0-sysroot");
+            builder.cp_r(&builder.initial_sysroot.join("lib"), &sysroot.join("lib"));
+        } else {
+            add_to_sysroot(builder, &libdir, &hostdir, &libstd_stamp(builder, compiler, target));
         }
     }
 }
diff --git a/src/bootstrap/src/core/build_steps/test.rs b/src/bootstrap/src/core/build_steps/test.rs
index 04728e2e00dcc..9733e39e1384f 100644
--- a/src/bootstrap/src/core/build_steps/test.rs
+++ b/src/bootstrap/src/core/build_steps/test.rs
@@ -1121,7 +1121,7 @@ impl Step for Tidy {
         if builder.config.channel == "dev" || builder.config.channel == "nightly" {
             builder.info("fmt check");
             if builder.initial_rustfmt().is_none() {
-                let inferred_rustfmt_dir = builder.initial_rustc.parent().unwrap();
+                let inferred_rustfmt_dir = builder.initial_sysroot.join("bin");
                 eprintln!(
                     "\
 ERROR: no `rustfmt` binary found in {PATH}
diff --git a/src/bootstrap/src/core/builder.rs b/src/bootstrap/src/core/builder.rs
index 4e20babc55a68..b7eb8815b6aef 100644
--- a/src/bootstrap/src/core/builder.rs
+++ b/src/bootstrap/src/core/builder.rs
@@ -1167,7 +1167,7 @@ impl<'a> Builder<'a> {
     }
 
     pub fn cargo_clippy_cmd(&self, run_compiler: Compiler) -> Command {
-        let initial_sysroot_bin = self.initial_rustc.parent().unwrap();
+        let initial_sysroot_bin = self.initial_sysroot.join("bin");
         // Set PATH to include the sysroot bin dir so clippy can find cargo.
         // FIXME: once rust-clippy#11944 lands on beta, set `CARGO` directly instead.
         let path = t!(env::join_paths(
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index fcdd742e69c22..700c77c97e4ad 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -186,6 +186,7 @@ pub struct Config {
 
     pub on_fail: Option<String>,
     pub stage: u32,
+    pub build_std_on_stage0: bool,
     pub keep_stage: Vec<u32>,
     pub keep_stage_std: Vec<u32>,
     pub src: PathBuf,
@@ -1219,6 +1220,7 @@ impl Config {
         config.incremental = flags.incremental;
         config.dry_run = if flags.dry_run { DryRun::UserSelected } else { DryRun::Disabled };
         config.dump_bootstrap_shims = flags.dump_bootstrap_shims;
+        config.build_std_on_stage0 = flags.build_std_on_stage0;
         config.keep_stage = flags.keep_stage;
         config.keep_stage_std = flags.keep_stage_std;
         config.color = flags.color;
diff --git a/src/bootstrap/src/core/config/flags.rs b/src/bootstrap/src/core/config/flags.rs
index 8af454001a64a..b9f5c2f08dc91 100644
--- a/src/bootstrap/src/core/config/flags.rs
+++ b/src/bootstrap/src/core/config/flags.rs
@@ -92,6 +92,9 @@ pub struct Flags {
     /// stage to build (indicates compiler to use/test, e.g., stage 0 uses the
     /// bootstrap compiler, stage 1 the stage 0 rustc artifacts, etc.)
     pub stage: Option<u32>,
+    /// Useful for library testing with the beta compiler (without building the stage 1 compiler)
+    #[arg(global(true), long)]
+    pub build_std_on_stage0: bool,
 
     #[arg(global(true), value_hint = clap::ValueHint::Other, long, value_name = "N")]
     /// stage(s) to keep without recompiling
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 327b4674acfdb..977fab5e25b72 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -111,4 +111,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "A new `optimized-compiler-builtins` option has been introduced. Whether to build llvm's `compiler-rt` from source is no longer implicitly controlled by git state. See the PR for more details.",
     },
+    ChangeInfo {
+        change_id: 119899,
+        severity: ChangeSeverity::Info,
+        summary: "Stage 0 std is now same as beta std rather than the compiled version from source (which is now stage 1). If you want to test/build std on stage 0, use `--build-std-on-stage0` flag (e.g., `x test --stage0 --build-std-on-stage0 alloc`).",
+    },
 ];
diff --git a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
index e2b66c2cff1d8..f399d5d5ff640 100644
--- a/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
+++ b/src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile
@@ -27,5 +27,5 @@ RUN echo "[rust]" > /config/nopt-std-config.toml
 RUN echo "optimize = false" >> /config/nopt-std-config.toml
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
-ENV SCRIPT python3 ../x.py test --stage 0 --config /config/nopt-std-config.toml library/std \
+ENV SCRIPT python3 ../x.py test --build-std-on-stage0 --stage 0 --config /config/nopt-std-config.toml library/std \
   && python3 ../x.py --stage 2 test
diff --git a/src/ci/docker/host-x86_64/mingw-check/Dockerfile b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
index f8fcda5070fab..8f29335b440cf 100644
--- a/src/ci/docker/host-x86_64/mingw-check/Dockerfile
+++ b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
@@ -49,7 +49,7 @@ ENV SCRIPT python3 ../x.py --stage 2 test src/tools/expand-yaml-anchors && \
            python3 ../x.py clippy --stage 0 -Awarnings && \
            python3 ../x.py build --stage 0 src/tools/build-manifest && \
            python3 ../x.py test --stage 0 src/tools/compiletest && \
-           python3 ../x.py test --stage 0 core alloc std test proc_macro && \
+           python3 ../x.py test --build-std-on-stage0 --stage 0 core alloc std test proc_macro && \
            # Build both public and internal documentation.
            RUSTDOCFLAGS=\"--document-private-items --document-hidden-items\" python3 ../x.py doc --stage 0 library && \
            mkdir -p /checkout/obj/staging/doc && \
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
index d8113e0672375..187f323d7a23c 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile
@@ -29,5 +29,5 @@ RUN echo "optimize = false" >> /config/nopt-std-config.toml
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
   --disable-optimize-tests \
   --set rust.test-compare-mode
-ENV SCRIPT python3 ../x.py test --stage 0 --config /config/nopt-std-config.toml library/std \
+ENV SCRIPT python3 ../x.py test --build-std-on-stage0 --stage 0 --config /config/nopt-std-config.toml library/std \
   && python3 ../x.py --stage 2 test
diff --git a/src/etc/completions/x.py.fish b/src/etc/completions/x.py.fish
index 9fc95fd09ba9f..acf4fe6476189 100644
--- a/src/etc/completions/x.py.fish
+++ b/src/etc/completions/x.py.fish
@@ -26,6 +26,7 @@ complete -c x.py -n "__fish_use_subcommand" -s i -l incremental -d 'use incremen
 complete -c x.py -n "__fish_use_subcommand" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_use_subcommand" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_use_subcommand" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_use_subcommand" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_use_subcommand" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_use_subcommand" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_use_subcommand" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -74,6 +75,7 @@ complete -c x.py -n "__fish_seen_subcommand_from build" -s i -l incremental -d '
 complete -c x.py -n "__fish_seen_subcommand_from build" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from build" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from build" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from build" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from build" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from build" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from build" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -109,6 +111,7 @@ complete -c x.py -n "__fish_seen_subcommand_from check" -s i -l incremental -d '
 complete -c x.py -n "__fish_seen_subcommand_from check" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from check" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from check" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from check" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from check" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from check" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from check" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -150,6 +153,7 @@ complete -c x.py -n "__fish_seen_subcommand_from clippy" -s i -l incremental -d
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from clippy" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from clippy" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -184,6 +188,7 @@ complete -c x.py -n "__fish_seen_subcommand_from fix" -s i -l incremental -d 'us
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from fix" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from fix" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -219,6 +224,7 @@ complete -c x.py -n "__fish_seen_subcommand_from fmt" -s i -l incremental -d 'us
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from fmt" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from fmt" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -255,6 +261,7 @@ complete -c x.py -n "__fish_seen_subcommand_from doc" -s i -l incremental -d 'us
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from doc" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from doc" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -302,6 +309,7 @@ complete -c x.py -n "__fish_seen_subcommand_from test" -s i -l incremental -d 'u
 complete -c x.py -n "__fish_seen_subcommand_from test" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from test" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from test" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from test" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from test" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from test" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from test" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -337,6 +345,7 @@ complete -c x.py -n "__fish_seen_subcommand_from bench" -s i -l incremental -d '
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from bench" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from bench" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -372,6 +381,7 @@ complete -c x.py -n "__fish_seen_subcommand_from clean" -s i -l incremental -d '
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from clean" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from clean" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -406,6 +416,7 @@ complete -c x.py -n "__fish_seen_subcommand_from dist" -s i -l incremental -d 'u
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from dist" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from dist" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -440,6 +451,7 @@ complete -c x.py -n "__fish_seen_subcommand_from install" -s i -l incremental -d
 complete -c x.py -n "__fish_seen_subcommand_from install" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from install" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from install" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from install" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from install" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from install" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from install" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -475,6 +487,7 @@ complete -c x.py -n "__fish_seen_subcommand_from run" -s i -l incremental -d 'us
 complete -c x.py -n "__fish_seen_subcommand_from run" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from run" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from run" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from run" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from run" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from run" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from run" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -509,6 +522,7 @@ complete -c x.py -n "__fish_seen_subcommand_from setup" -s i -l incremental -d '
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from setup" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from setup" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
@@ -544,6 +558,7 @@ complete -c x.py -n "__fish_seen_subcommand_from suggest" -s i -l incremental -d
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l include-default-paths -d 'include default paths in addition to the provided ones'
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l dry-run -d 'dry run; don\'t build anything'
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l dump-bootstrap-shims -d 'Indicates whether to dump the work done from bootstrap shims'
+complete -c x.py -n "__fish_seen_subcommand_from suggest" -l build-std-on-stage0 -d 'Useful for library testing with the beta compiler (without building the stage 1 compiler)'
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l json-output -d 'use message-format=json'
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l bypass-bootstrap-lock -d 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)'
 complete -c x.py -n "__fish_seen_subcommand_from suggest" -l llvm-profile-generate -d 'generate PGO profile with llvm built for rustc'
diff --git a/src/etc/completions/x.py.ps1 b/src/etc/completions/x.py.ps1
index 6359b7ff086a9..7a76168bb74bb 100644
--- a/src/etc/completions/x.py.ps1
+++ b/src/etc/completions/x.py.ps1
@@ -52,6 +52,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -107,6 +108,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -149,6 +151,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -197,6 +200,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -238,6 +242,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -280,6 +285,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -323,6 +329,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -377,6 +384,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -419,6 +427,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -461,6 +470,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -502,6 +512,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -543,6 +554,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -585,6 +597,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -626,6 +639,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
@@ -668,6 +682,7 @@ Register-ArgumentCompleter -Native -CommandName 'x.py' -ScriptBlock {
             [CompletionResult]::new('--include-default-paths', 'include-default-paths', [CompletionResultType]::ParameterName, 'include default paths in addition to the provided ones')
             [CompletionResult]::new('--dry-run', 'dry-run', [CompletionResultType]::ParameterName, 'dry run; don''t build anything')
             [CompletionResult]::new('--dump-bootstrap-shims', 'dump-bootstrap-shims', [CompletionResultType]::ParameterName, 'Indicates whether to dump the work done from bootstrap shims')
+            [CompletionResult]::new('--build-std-on-stage0', 'build-std-on-stage0', [CompletionResultType]::ParameterName, 'Useful for library testing with the beta compiler (without building the stage 1 compiler)')
             [CompletionResult]::new('--json-output', 'json-output', [CompletionResultType]::ParameterName, 'use message-format=json')
             [CompletionResult]::new('--bypass-bootstrap-lock', 'bypass-bootstrap-lock', [CompletionResultType]::ParameterName, 'Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)')
             [CompletionResult]::new('--llvm-profile-generate', 'llvm-profile-generate', [CompletionResultType]::ParameterName, 'generate PGO profile with llvm built for rustc')
diff --git a/src/etc/completions/x.py.sh b/src/etc/completions/x.py.sh
index e1436dcde6704..9f3e40d630e7f 100644
--- a/src/etc/completions/x.py.sh
+++ b/src/etc/completions/x.py.sh
@@ -61,7 +61,7 @@ _x.py() {
 
     case "${cmd}" in
         x.py)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]... build check clippy fix fmt doc test bench clean dist install run setup suggest"
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]... build check clippy fix fmt doc test bench clean dist install run setup suggest"
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 1 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -171,7 +171,7 @@ _x.py() {
             return 0
             ;;
         x.py__bench)
-            opts="-v -i -j -h --test-args --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --test-args --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -285,7 +285,7 @@ _x.py() {
             return 0
             ;;
         x.py__build)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -395,7 +395,7 @@ _x.py() {
             return 0
             ;;
         x.py__check)
-            opts="-v -i -j -h --all-targets --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --all-targets --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -505,7 +505,7 @@ _x.py() {
             return 0
             ;;
         x.py__clean)
-            opts="-v -i -j -h --all --stage --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --all --stage --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -615,7 +615,7 @@ _x.py() {
             return 0
             ;;
         x.py__clippy)
-            opts="-A -D -W -F -v -i -j -h --fix --allow-dirty --allow-staged --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-A -D -W -F -v -i -j -h --fix --allow-dirty --allow-staged --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -741,7 +741,7 @@ _x.py() {
             return 0
             ;;
         x.py__dist)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -851,7 +851,7 @@ _x.py() {
             return 0
             ;;
         x.py__doc)
-            opts="-v -i -j -h --open --json --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --open --json --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -961,7 +961,7 @@ _x.py() {
             return 0
             ;;
         x.py__fix)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1071,7 +1071,7 @@ _x.py() {
             return 0
             ;;
         x.py__fmt)
-            opts="-v -i -j -h --check --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --check --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1181,7 +1181,7 @@ _x.py() {
             return 0
             ;;
         x.py__install)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1291,7 +1291,7 @@ _x.py() {
             return 0
             ;;
         x.py__run)
-            opts="-v -i -j -h --args --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --args --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1405,7 +1405,7 @@ _x.py() {
             return 0
             ;;
         x.py__setup)
-            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [<PROFILE>|hook|vscode|link] [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [<PROFILE>|hook|vscode|link] [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1515,7 +1515,7 @@ _x.py() {
             return 0
             ;;
         x.py__suggest)
-            opts="-v -i -j -h --run --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --run --verbose --incremental --config --build-dir --build --host --target --exclude --skip --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
@@ -1625,7 +1625,7 @@ _x.py() {
             return 0
             ;;
         x.py__test)
-            opts="-v -i -j -h --no-fail-fast --skip --test-args --rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --verbose --incremental --config --build-dir --build --host --target --exclude --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
+            opts="-v -i -j -h --no-fail-fast --skip --test-args --rustc-args --no-doc --doc --bless --extra-checks --force-rerun --only-modified --compare-mode --pass --run --rustfix-coverage --verbose --incremental --config --build-dir --build --host --target --exclude --include-default-paths --rustc-error-format --on-fail --dry-run --dump-bootstrap-shims --stage --build-std-on-stage0 --keep-stage --keep-stage-std --src --jobs --warnings --error-format --json-output --color --bypass-bootstrap-lock --llvm-skip-rebuild --rust-profile-generate --rust-profile-use --llvm-profile-use --llvm-profile-generate --enable-bolt-settings --skip-stage0-validation --reproducible-artifact --set --help [PATHS]... [ARGS]..."
             if [[ ${cur} == -* || ${COMP_CWORD} -eq 2 ]] ; then
                 COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                 return 0
diff --git a/src/etc/completions/x.py.zsh b/src/etc/completions/x.py.zsh
index ea7e4ba6758f5..712f76aa98336 100644
--- a/src/etc/completions/x.py.zsh
+++ b/src/etc/completions/x.py.zsh
@@ -46,6 +46,7 @@ _x.py() {
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -97,6 +98,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -141,6 +143,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -191,6 +194,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -234,6 +238,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -278,6 +283,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -323,6 +329,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -379,6 +386,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -423,6 +431,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -467,6 +476,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -510,6 +520,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -553,6 +564,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -597,6 +609,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -640,6 +653,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \
@@ -685,6 +699,7 @@ _arguments "${_arguments_options[@]}" \
 '--include-default-paths[include default paths in addition to the provided ones]' \
 '--dry-run[dry run; don'\''t build anything]' \
 '--dump-bootstrap-shims[Indicates whether to dump the work done from bootstrap shims]' \
+'--build-std-on-stage0[Useful for library testing with the beta compiler (without building the stage 1 compiler)]' \
 '--json-output[use message-format=json]' \
 '--bypass-bootstrap-lock[Bootstrap uses this value to decide whether it should bypass locking the build process. This is rarely needed (e.g., compiling the std library for different targets in parallel)]' \
 '--llvm-profile-generate[generate PGO profile with llvm built for rustc]' \