diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e1a948c92f..740118bb4a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -117,6 +117,41 @@ jobs:
       - name: rustdoc
         run: RUSTDOCFLAGS="-Dwarnings" ./miri doc --document-private-items
 
+  bootstrap:
+    name: bootstrap build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      # Deliberately skipping `./.github/workflows/setup` as we do our own setup
+      - name: Add cache for cargo
+        id: cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            # Taken from <https://doc.rust-lang.org/nightly/cargo/guide/cargo-home.html#caching-the-cargo-home-in-ci>.
+            # Cache package/registry information
+            ~/.cargo/registry/index
+            ~/.cargo/registry/cache
+            ~/.cargo/git/db
+            # Cache bootstrap downloads
+            ../rust/build/cache
+          key: cargo-bootstrap-${{ hashFiles('rust-version') }}
+          restore-keys: cargo-bootstrap
+      - name: prepare build environment
+        run: |
+          MIRIDIR=$(pwd)
+          cd ..
+          # Bootstrap needs at least depth 2 to function.
+          git clone https://github.com/rust-lang/rust/ rust --depth 2 --revision $(cat "$MIRIDIR/rust-version")
+          cd rust
+          # Replace the in-tree Miri with the current version.
+          rm src/tools/miri -rf
+          ln -s "$MIRIDIR" src/tools/miri
+      - name: check build
+        run: |
+          cd ../rust # ./x does not seem to like being invoked from elsewhere
+          ./x check miri
+
   coverage:
     name: coverage report
     runs-on: ubuntu-latest
@@ -130,7 +165,7 @@ jobs:
   # ALL THE PREVIOUS JOBS NEED TO BE ADDED TO THE `needs` SECTION OF THIS JOB!
   # And they should be added below in `cron-fail-notify` as well.
   conclusion:
-    needs: [test, style, coverage]
+    needs: [test, style, bootstrap, coverage]
     # We need to ensure this job does *not* get skipped if its dependencies fail,
     # because a skipped job is considered a success by GitHub. So we have to
     # overwrite `if:`. We use `!cancelled()` to ensure the job does still not get run
@@ -211,7 +246,7 @@ jobs:
   cron-fail-notify:
     name: cronjob failure notification
     runs-on: ubuntu-latest
-    needs: [test, style, coverage]
+    needs: [test, style, bootstrap, coverage]
     if: ${{ github.event_name == 'schedule' && failure() }}
     steps:
       # Send a Zulip notification
diff --git a/miri-script/src/commands.rs b/miri-script/src/commands.rs
index ee09b9b4b7..f1b5229312 100644
--- a/miri-script/src/commands.rs
+++ b/miri-script/src/commands.rs
@@ -130,15 +130,15 @@ impl Command {
         let new_commit = sh.read_file("rust-version")?.trim().to_owned();
         let current_commit = {
             let rustc_info = cmd!(sh, "rustc +miri --version -v").read();
-            if rustc_info.is_err() {
-                None
-            } else {
-                let metadata = rustc_version::version_meta_for(&rustc_info.unwrap())?;
+            if let Ok(rustc_info) = rustc_info {
+                let metadata = rustc_version::version_meta_for(&rustc_info)?;
                 Some(
                     metadata
                         .commit_hash
                         .ok_or_else(|| anyhow!("rustc metadata did not contain commit hash"))?,
                 )
+            } else {
+                None
             }
         };
         // Check if we already are at that commit.
diff --git a/rust-version b/rust-version
index 0eb16a943d..7333f7968f 100644
--- a/rust-version
+++ b/rust-version
@@ -1 +1 @@
-3f1552a273e43e15f6ed240d00e1efdd6a53e65e
+ec38671075266e9cee0348701da2e133379e7c6c
diff --git a/src/clock.rs b/src/clock.rs
index 47608f873a..dbbe741a07 100644
--- a/src/clock.rs
+++ b/src/clock.rs
@@ -46,7 +46,21 @@ impl Instant {
                 InstantKind::Virtual { nanoseconds: earlier },
             ) => {
                 let duration = nanoseconds.saturating_sub(earlier);
-                Duration::from_nanos_u128(duration)
+                cfg_select! {
+                    bootstrap => {
+                         // `Duration` does not provide a nice constructor from a `u128` of nanoseconds,
+                        // so we have to implement this ourselves.
+                        // It is possible for second to overflow because u64::MAX < (u128::MAX / 1e9).
+                        // It will be saturated to u64::MAX seconds if the value after division exceeds u64::MAX.
+                        let seconds = u64::try_from(duration / 1_000_000_000).unwrap_or(u64::MAX);
+                        // It is impossible for nanosecond to overflow because u32::MAX > 1e9.
+                        let nanosecond = u32::try_from(duration.wrapping_rem(1_000_000_000)).unwrap();
+                        Duration::new(seconds, nanosecond)
+                    }
+                    _ => {
+                        Duration::from_nanos_u128(duration)
+                    }
+                }
             }
             _ => panic!("all `Instant` must be of the same kind"),
         }
diff --git a/src/lib.rs b/src/lib.rs
index dbc2a99593..7f5f25b9f6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -18,7 +18,7 @@
 #![feature(derive_coerce_pointee)]
 #![feature(arbitrary_self_types)]
 #![feature(iter_advance_by)]
-#![feature(duration_from_nanos_u128)]
+#![cfg_attr(not(bootstrap), feature(duration_from_nanos_u128))]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,