diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 85937a8e4445..45c0bea370ac 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -95,15 +95,9 @@ jobs:
         # We need a toolchain that can actually build Miri, just a nightly won't do.
         run: |
           cargo install rustup-toolchain-install-master # TODO: cache this?
-          ./rustup-toolchain "" -c clippy -c rustfmt
-      - name: rustfmt (miri, ui_test)
-        run: cargo fmt --all --check
-      - name: rustfmt (everything else)
-        # TODO: Add `tests` (work in progress).
-        # Maybe change to `find . -name '*.rs'`, superseding the previous step.
-        run: |
-          find bench-cargo-miri benches cargo-miri test-cargo-miri -name '*.rs' \
-            | xargs rustfmt --edition=2021 --config-path ./rustfmt.toml --check
+          ./rustup-toolchain "" -c clippy
+      - name: rustfmt
+        run: ./miri fmt --check
       - name: clippy (miri)
         run: cargo clippy --all-targets -- -D warnings
       #- name: Clippy (ui_test)
diff --git a/miri b/miri
index 5c9cb81885c9..e89a9e380fff 100755
--- a/miri
+++ b/miri
@@ -21,10 +21,13 @@ to the final `cargo test` invocation.
 ./miri run <flags>:
 Build miri, set up a sysroot and then run the driver with the given <flags>.
 
-All commands also exist in a "-debug" variant (e.g. "./miri run-debug
+The commands above also exist in a "-debug" variant (e.g. "./miri run-debug
 <flags>") which uses debug builds instead of release builds, for faster build
 times and slower execution times.
 
+./miri fmt <flags>:
+Format all sources and tests.  <flags> are passed to `rustfmt`.
+
   ENVIRONMENT VARIABLES
 
 MIRI_SYSROOT:
@@ -156,6 +159,10 @@ run|run-debug)
     # Then run the actual command.
     exec cargo run $CARGO_BUILD_FLAGS -- --sysroot "$MIRI_SYSROOT" "$@"
     ;;
+fmt)
+    find "$MIRIDIR" -not \( -name target -prune \) -name '*.rs' \
+        | xargs rustfmt --edition=2021 --config-path "$MIRIDIR/rustfmt.toml" "$@"
+    ;;
 *)
     if [ -n "$COMMAND" ]; then
       echo "Unknown command: $COMMAND"
diff --git a/rustup-toolchain b/rustup-toolchain
index ca5508e225a1..34472c727f62 100755
--- a/rustup-toolchain
+++ b/rustup-toolchain
@@ -42,7 +42,7 @@ fi
 
 # Install and setup new toolchain.
 rustup toolchain uninstall miri
-rustup-toolchain-install-master -n miri -c cargo -c rust-src -c rustc-dev -c llvm-tools "$@" -- "$NEW_COMMIT"
+rustup-toolchain-install-master -n miri -c cargo -c rust-src -c rustc-dev -c llvm-tools -c rustfmt "$@" -- "$NEW_COMMIT"
 rustup override set miri
 
 # Cleanup.
diff --git a/tests/fail/abort-terminator.rs b/tests/fail/abort-terminator.rs
index fcdeaa0ffea2..c954443a2762 100644
--- a/tests/fail/abort-terminator.rs
+++ b/tests/fail/abort-terminator.rs
@@ -1,6 +1,7 @@
 #![feature(c_unwind)]
 
-extern "C" fn panic_abort() { //~ ERROR: the program aborted
+extern "C" fn panic_abort() {
+    //~^ ERROR: the program aborted
     panic!()
 }
 
diff --git a/tests/fail/abort-terminator.stderr b/tests/fail/abort-terminator.stderr
index b096775e61d3..ec9ce76685b5 100644
--- a/tests/fail/abort-terminator.stderr
+++ b/tests/fail/abort-terminator.stderr
@@ -4,6 +4,7 @@ error: abnormal termination: the program aborted execution
   --> $DIR/abort-terminator.rs:LL:CC
    |
 LL | / extern "C" fn panic_abort() {
+LL | |
 LL | |     panic!()
 LL | | }
    | |_^ the program aborted execution
diff --git a/tests/fail/concurrency/unwind_top_of_stack.rs b/tests/fail/concurrency/unwind_top_of_stack.rs
index 9e6088be7a7e..39f7ae8bafb9 100644
--- a/tests/fail/concurrency/unwind_top_of_stack.rs
+++ b/tests/fail/concurrency/unwind_top_of_stack.rs
@@ -10,7 +10,7 @@
 use std::{mem, ptr};
 
 extern "C-unwind" fn thread_start(_null: *mut libc::c_void) -> *mut libc::c_void {
-//~^ ERROR unwinding past the topmost frame of the stack
+    //~^ ERROR unwinding past the topmost frame of the stack
     panic!()
 }
 
diff --git a/tests/pass/concurrency/sync_nopreempt.rs b/tests/pass/concurrency/sync_nopreempt.rs
index 38dbeb575d64..8895d62df95f 100644
--- a/tests/pass/concurrency/sync_nopreempt.rs
+++ b/tests/pass/concurrency/sync_nopreempt.rs
@@ -2,7 +2,7 @@
 // We are making scheduler assumptions here.
 // compile-flags: -Zmiri-strict-provenance -Zmiri-preemption-rate=0
 
-use std::sync::{Condvar, Mutex, Arc};
+use std::sync::{Arc, Condvar, Mutex};
 use std::thread;
 
 fn check_conditional_variables_notify_all() {