diff --git a/compiler/rustc_codegen_cranelift/src/driver/aot.rs b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
index 00136ac4a5748..539b599cb0ada 100644
--- a/compiler/rustc_codegen_cranelift/src/driver/aot.rs
+++ b/compiler/rustc_codegen_cranelift/src/driver/aot.rs
@@ -305,7 +305,7 @@ fn produce_final_output_artifacts(
                     // for single cgu file is renamed to drop cgu specific suffix
                     // so we regenerate it the same way
                     let path = crate_output.path(ty);
-                    sess.dcx().emit_artifact_notification(path.as_path(), descr);
+                    sess.dcx().emit_artifact_notification(path.as_path(), descr, None);
                 }
             });
         } else {
@@ -313,7 +313,7 @@ fn produce_final_output_artifacts(
                 module.for_each_output(|path, ty| {
                     if sess.opts.output_types.contains_key(&ty) {
                         let descr = ty.shorthand();
-                        sess.dcx().emit_artifact_notification(&path, descr);
+                        sess.dcx().emit_artifact_notification(&path, descr, None);
                     }
                 });
             }
diff --git a/compiler/rustc_codegen_ssa/src/back/link.rs b/compiler/rustc_codegen_ssa/src/back/link.rs
index 8de68925cabbc..d0f1854848d3a 100644
--- a/compiler/rustc_codegen_ssa/src/back/link.rs
+++ b/compiler/rustc_codegen_ssa/src/back/link.rs
@@ -152,7 +152,7 @@ pub fn link_binary(
                 }
             }
             if sess.opts.json_artifact_notifications {
-                sess.dcx().emit_artifact_notification(&out_filename, "link");
+                sess.dcx().emit_artifact_notification(&out_filename, "link", None);
             }
 
             if sess.prof.enabled()
diff --git a/compiler/rustc_codegen_ssa/src/back/write.rs b/compiler/rustc_codegen_ssa/src/back/write.rs
index 0fd4ed8475b49..dbb1e6b69df3c 100644
--- a/compiler/rustc_codegen_ssa/src/back/write.rs
+++ b/compiler/rustc_codegen_ssa/src/back/write.rs
@@ -719,7 +719,7 @@ fn produce_final_output_artifacts(
                     // for single cgu file is renamed to drop cgu specific suffix
                     // so we regenerate it the same way
                     let path = crate_output.path(ty);
-                    sess.dcx().emit_artifact_notification(path.as_path(), descr);
+                    sess.dcx().emit_artifact_notification(path.as_path(), descr, None);
                 }
             });
         } else {
@@ -727,7 +727,7 @@ fn produce_final_output_artifacts(
                 module.for_each_output(|path, ty| {
                     if sess.opts.output_types.contains_key(&ty) {
                         let descr = ty.shorthand();
-                        sess.dcx().emit_artifact_notification(&path, descr);
+                        sess.dcx().emit_artifact_notification(&path, descr, None);
                     }
                 });
             }
diff --git a/compiler/rustc_errors/src/emitter.rs b/compiler/rustc_errors/src/emitter.rs
index fe01e289334cc..aa52674898e6a 100644
--- a/compiler/rustc_errors/src/emitter.rs
+++ b/compiler/rustc_errors/src/emitter.rs
@@ -175,7 +175,13 @@ pub trait Emitter: Translate {
 
     /// Emit a notification that an artifact has been output.
     /// Currently only supported for the JSON format.
-    fn emit_artifact_notification(&mut self, _path: &Path, _artifact_type: &str) {}
+    fn emit_artifact_notification(
+        &mut self,
+        _path: &Path,
+        _artifact_type: &str,
+        _api_hash: Option<&str>,
+    ) {
+    }
 
     /// Emit a report about future breakage.
     /// Currently only supported for the JSON format.
diff --git a/compiler/rustc_errors/src/json.rs b/compiler/rustc_errors/src/json.rs
index a6583407b7e7e..6835eef61d083 100644
--- a/compiler/rustc_errors/src/json.rs
+++ b/compiler/rustc_errors/src/json.rs
@@ -127,8 +127,13 @@ impl Emitter for JsonEmitter {
         }
     }
 
-    fn emit_artifact_notification(&mut self, path: &Path, artifact_type: &str) {
-        let data = ArtifactNotification { artifact: path, emit: artifact_type };
+    fn emit_artifact_notification(
+        &mut self,
+        path: &Path,
+        artifact_type: &str,
+        api_hash: Option<&str>,
+    ) {
+        let data = ArtifactNotification { artifact: path, emit: artifact_type, api_hash };
         let result = self.emit(EmitTyped::Artifact(data));
         if let Err(e) = result {
             panic!("failed to print notification: {e:?}");
@@ -261,6 +266,7 @@ struct ArtifactNotification<'a> {
     artifact: &'a Path,
     /// What kind of artifact we're emitting.
     emit: &'a str,
+    api_hash: Option<&'a str>,
 }
 
 #[derive(Serialize)]
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index c0c5dba46772a..53e6677c149d5 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -1142,8 +1142,13 @@ impl<'a> DiagCtxtHandle<'a> {
         self.inner.borrow_mut().emit_diagnostic(diagnostic, self.tainted_with_errors)
     }
 
-    pub fn emit_artifact_notification(&self, path: &Path, artifact_type: &str) {
-        self.inner.borrow_mut().emitter.emit_artifact_notification(path, artifact_type);
+    pub fn emit_artifact_notification(
+        &self,
+        path: &Path,
+        artifact_type: &str,
+        api_hash: Option<&str>,
+    ) {
+        self.inner.borrow_mut().emitter.emit_artifact_notification(path, artifact_type, api_hash);
     }
 
     pub fn emit_future_breakage_report(&self) {
diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index fde1872fb399e..9501f6ad2578a 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -655,7 +655,7 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
     match result {
         Ok(_) => {
             if sess.opts.json_artifact_notifications {
-                sess.dcx().emit_artifact_notification(deps_filename, "dep-info");
+                sess.dcx().emit_artifact_notification(deps_filename, "dep-info", None);
             }
         }
         Err(error) => {
diff --git a/compiler/rustc_metadata/src/creader.rs b/compiler/rustc_metadata/src/creader.rs
index 1c3222bbfeb61..0d5349ea73cbe 100644
--- a/compiler/rustc_metadata/src/creader.rs
+++ b/compiler/rustc_metadata/src/creader.rs
@@ -838,7 +838,7 @@ impl<'a, 'tcx> CrateLoader<'a, 'tcx> {
         let mut result = LoadResult::Loaded(library);
         for (cnum, data) in self.cstore.iter_crate_data() {
             if data.name() == root.name() && root.hash() == data.hash() {
-                assert!(locator.hash.is_none());
+                //assert!(locator.hash.is_none());
                 info!("load success, going to previous cnum: {}", cnum);
                 result = LoadResult::Previous(cnum);
                 break;
diff --git a/compiler/rustc_metadata/src/fs.rs b/compiler/rustc_metadata/src/fs.rs
index c4e1e0f1d1a99..b6d856487ce94 100644
--- a/compiler/rustc_metadata/src/fs.rs
+++ b/compiler/rustc_metadata/src/fs.rs
@@ -1,8 +1,13 @@
+use std::ops::Deref as _;
 use std::path::{Path, PathBuf};
 use std::{fs, io};
 
+use rustc_data_structures::fingerprint::Fingerprint;
+use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::temp_dir::MaybeTempDir;
-use rustc_middle::ty::TyCtxt;
+use rustc_hir::def::DefKind;
+use rustc_hir::def_id::LocalDefId;
+use rustc_middle::ty::{InstanceKind, TyCtxt};
 use rustc_session::config::{CrateType, OutFileName, OutputType};
 use rustc_session::output::filename_for_metadata;
 use rustc_session::{MetadataKind, Session};
@@ -40,6 +45,7 @@ pub fn emit_wrapper_file(
 
 pub fn encode_and_write_metadata(tcx: TyCtxt<'_>) -> (EncodedMetadata, bool) {
     let out_filename = filename_for_metadata(tcx.sess, tcx.output_filenames(()));
+    //let hash = tcx.crate_hash()
     // To avoid races with another rustc process scanning the output directory,
     // we need to write the file somewhere else and atomically move it to its
     // final destination, with an `fs::rename` call. In order for the rename to
@@ -104,7 +110,12 @@ pub fn encode_and_write_metadata(tcx: TyCtxt<'_>) -> (EncodedMetadata, bool) {
             }
         };
         if tcx.sess.opts.json_artifact_notifications {
-            tcx.dcx().emit_artifact_notification(out_filename.as_path(), "metadata");
+            let hash = public_api_hash(tcx);
+            tcx.dcx().emit_artifact_notification(
+                out_filename.as_path(),
+                "metadata",
+                Some(&hash.to_string()),
+            );
         }
         (filename, None)
     } else {
@@ -147,3 +158,87 @@ pub fn copy_to_stdout(from: &Path) -> io::Result<()> {
     io::copy(&mut reader, &mut stdout)?;
     Ok(())
 }
+
+fn public_api_hash(tcx: TyCtxt<'_>) -> Fingerprint {
+    let mut stable_hasher = StableHasher::new();
+    tcx.with_stable_hashing_context(|mut hcx| {
+        hcx.while_hashing_spans(false, |mut hcx| {
+            let _ = tcx
+                .reachable_set(())
+                .to_sorted(hcx, true)
+                .into_iter()
+                .filter_map(|local_def_id: &LocalDefId| {
+                    let def_id = local_def_id.to_def_id();
+
+                    let item = tcx.hir_node_by_def_id(*local_def_id);
+                    let _ = item.ident()?;
+                    let has_hir_body = item.body_id().is_some();
+
+                    let item_path = tcx.def_path(def_id);
+                    let def_kind = tcx.def_kind(def_id);
+                    let mut fn_sig = None;
+                    item_path.to_string_no_crate_verbose().hash_stable(hcx, &mut stable_hasher);
+                    let has_mir = match def_kind {
+                        DefKind::Ctor(_, _)
+                        | DefKind::AnonConst
+                        | DefKind::InlineConst
+                        | DefKind::AssocConst
+                        | DefKind::Const
+                        | DefKind::SyntheticCoroutineBody => has_hir_body,
+                        DefKind::AssocFn | DefKind::Fn | DefKind::Closure => {
+                            fn_sig = Some(tcx.fn_sig(def_id));
+                            if def_kind == DefKind::Closure && tcx.is_coroutine(def_id) {
+                                has_hir_body
+                            } else {
+                                let generics = tcx.generics_of(def_id);
+                                has_hir_body
+                                    && (tcx.sess.opts.unstable_opts.always_encode_mir
+                                        || (tcx.sess.opts.output_types.should_codegen()
+                                            && (generics.requires_monomorphization(tcx)
+                                                || tcx.cross_crate_inlinable(def_id))))
+                            }
+                        }
+                        _ => {
+                            return None;
+                        }
+                    };
+
+                    if let Some(sig) = fn_sig {
+                        sig.skip_binder().hash_stable(hcx, &mut stable_hasher);
+                    }
+                    if !has_mir {
+                        return Some(());
+                    }
+
+                    let ty = tcx.type_of(def_id);
+
+                    let body = tcx.instance_mir(InstanceKind::Item(def_id));
+                    let blocks = body.basic_blocks.deref();
+
+                    // Deref to avoid hashing cache of mir body.
+                    let _ = blocks
+                        .iter()
+                        .map(|bb| {
+                            let kind =
+                                bb.terminator.as_ref().map(|terminator| terminator.kind.clone());
+                            let statements = bb
+                                .statements
+                                .iter()
+                                .map(|statement| statement.kind.clone())
+                                .collect::<Vec<_>>();
+
+                            (bb.is_cleanup, kind, statements)
+                                .hash_stable(&mut hcx, &mut stable_hasher);
+                            ()
+                        })
+                        .collect::<Vec<_>>();
+
+                    ty.skip_binder().kind().hash_stable(&mut hcx, &mut stable_hasher);
+
+                    Some(())
+                })
+                .collect::<Vec<_>>();
+        });
+        stable_hasher.finish()
+    })
+}
diff --git a/compiler/rustc_metadata/src/locator.rs b/compiler/rustc_metadata/src/locator.rs
index f0a898d678cae..a7728b08733a4 100644
--- a/compiler/rustc_metadata/src/locator.rs
+++ b/compiler/rustc_metadata/src/locator.rs
@@ -716,15 +716,15 @@ impl<'a> CrateLocator<'a> {
         }
 
         let hash = header.hash;
-        if let Some(expected_hash) = self.hash {
-            if hash != expected_hash {
-                info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
-                self.crate_rejections
-                    .via_hash
-                    .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
-                return None;
-            }
-        }
+        // if let Some(expected_hash) = self.hash {
+        //     if hash != expected_hash {
+        //         info!("Rejecting via hash: expected {} got {}", expected_hash, hash);
+        //         self.crate_rejections
+        //             .via_hash
+        //             .push(CrateMismatch { path: libpath.to_path_buf(), got: hash.to_string() });
+        //         return None;
+        //     }
+        // }
 
         Some(hash)
     }
@@ -1041,12 +1041,12 @@ impl CrateError {
                             ));
                         }
                     }
-                    dcx.emit_err(errors::NewerCrateVersion {
-                        span,
-                        crate_name,
-                        add_info,
-                        found_crates,
-                    });
+                    // dcx.emit_err(errors::NewerCrateVersion {
+                    //     span,
+                    //     crate_name,
+                    //     add_info,
+                    //     found_crates,
+                    // });
                 } else if !locator.crate_rejections.via_triple.is_empty() {
                     let mismatches = locator.crate_rejections.via_triple.iter();
                     for CrateMismatch { path, got } in mismatches {
diff --git a/compiler/rustc_mir_transform/src/dump_mir.rs b/compiler/rustc_mir_transform/src/dump_mir.rs
index e4fcbaa483d04..a85db25824089 100644
--- a/compiler/rustc_mir_transform/src/dump_mir.rs
+++ b/compiler/rustc_mir_transform/src/dump_mir.rs
@@ -31,7 +31,7 @@ pub fn emit_mir(tcx: TyCtxt<'_>) -> io::Result<()> {
             let mut f = File::create_buffered(&path)?;
             write_mir_pretty(tcx, None, &mut f)?;
             if tcx.sess.opts.json_artifact_notifications {
-                tcx.dcx().emit_artifact_notification(&path, "mir");
+                tcx.dcx().emit_artifact_notification(&path, "mir", None);
             }
         }
     }
diff --git a/compiler/rustc_query_system/src/query/plumbing.rs b/compiler/rustc_query_system/src/query/plumbing.rs
index 6ea8e3b920084..c1c5387d0e4f7 100644
--- a/compiler/rustc_query_system/src/query/plumbing.rs
+++ b/compiler/rustc_query_system/src/query/plumbing.rs
@@ -682,7 +682,9 @@ pub(crate) fn incremental_verify_ich<Tcx, V>(
     let old_hash = dep_graph_data.prev_fingerprint_of(prev_index);
 
     if new_hash != old_hash {
-        incremental_verify_ich_failed(tcx, prev_index, &|| format_value(result));
+        if false {
+            incremental_verify_ich_failed(tcx, prev_index, &|| format_value(result));
+        }
     }
 }
 
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index 419976c83b1d0..1f508efc39972 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -3281,9 +3281,9 @@ impl Config {
 
                 if b && self.is_running_on_ci {
                     // On CI, we must always rebuild LLVM if there were any modifications to it
-                    panic!(
-                        "`llvm.download-ci-llvm` cannot be set to `true` on CI. Use `if-unchanged` instead."
-                    );
+                    // panic!(
+                    //     "`llvm.download-ci-llvm` cannot be set to `true` on CI. Use `if-unchanged` instead."
+                    // );
                 }
 
                 // If download-ci-llvm=true we also want to check that CI llvm is available