diff --git a/Cargo.lock b/Cargo.lock
index 58d95f927bf95..a9fdf8926ee03 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5697,6 +5697,7 @@ dependencies = [
 name = "tidy"
 version = "0.1.0"
 dependencies = [
+ "build_helper",
  "cargo_metadata 0.15.4",
  "ignore",
  "miropt-test-tools",
diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index 63963b0bd1ced..c5204a9fee728 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -5,6 +5,7 @@ edition = "2021"
 autobins = false
 
 [dependencies]
+build_helper = { path = "../build_helper" }
 cargo_metadata = "0.15"
 regex = "1"
 miropt-test-tools = { path = "../miropt-test-tools" }
diff --git a/src/tools/tidy/src/deps.rs b/src/tools/tidy/src/deps.rs
index 2dd3d17f9e3e7..eb53c0d0b7726 100644
--- a/src/tools/tidy/src/deps.rs
+++ b/src/tools/tidy/src/deps.rs
@@ -1,7 +1,9 @@
 //! Checks the licenses of third-party dependencies.
 
+use build_helper::ci::CiEnv;
 use cargo_metadata::{Metadata, Package, PackageId};
 use std::collections::HashSet;
+use std::fs::read_dir;
 use std::path::Path;
 
 /// These are licenses that are allowed for all crates, including the runtime,
@@ -46,30 +48,37 @@ type ExceptionList = &'static [(&'static str, &'static str)];
 /// * Optionally a tuple of:
 ///     * A list of crates for which dependencies need to be explicitly allowed.
 ///     * The list of allowed dependencies.
+/// * An indication of whether it is a submodule or not.
 // FIXME auto detect all cargo workspaces
-pub(crate) const WORKSPACES: &[(&str, ExceptionList, Option<(&[&str], &[&str])>)] = &[
+pub(crate) const WORKSPACES: &[(&str, ExceptionList, Option<(&[&str], &[&str])>, bool)] = &[
     // The root workspace has to be first for check_rustfix to work.
-    (".", EXCEPTIONS, Some((&["rustc-main"], PERMITTED_RUSTC_DEPENDENCIES))),
+    (".", EXCEPTIONS, Some((&["rustc-main"], PERMITTED_RUSTC_DEPENDENCIES)), false),
     // Outside of the alphabetical section because rustfmt formats it using multiple lines.
     (
         "compiler/rustc_codegen_cranelift",
         EXCEPTIONS_CRANELIFT,
         Some((&["rustc_codegen_cranelift"], PERMITTED_CRANELIFT_DEPENDENCIES)),
+        false,
     ),
     // tidy-alphabetical-start
-    ("compiler/rustc_codegen_gcc", EXCEPTIONS_GCC, None),
+    ("compiler/rustc_codegen_gcc", EXCEPTIONS_GCC, None, false),
     //("library/backtrace", &[], None), // FIXME uncomment once rust-lang/backtrace#562 has been synced back to the rust repo
     //("library/portable-simd", &[], None), // FIXME uncomment once rust-lang/portable-simd#363 has been synced back to the rust repo
     //("library/stdarch", EXCEPTIONS_STDARCH, None), // FIXME uncomment once rust-lang/stdarch#1462 has been synced back to the rust repo
-    ("src/bootstrap", EXCEPTIONS_BOOTSTRAP, None),
-    ("src/ci/docker/host-x86_64/test-various/uefi_qemu_test", EXCEPTIONS_UEFI_QEMU_TEST, None),
+    ("src/bootstrap", EXCEPTIONS_BOOTSTRAP, None, false),
+    (
+        "src/ci/docker/host-x86_64/test-various/uefi_qemu_test",
+        EXCEPTIONS_UEFI_QEMU_TEST,
+        None,
+        false,
+    ),
     //("src/etc/test-float-parse", &[], None), // FIXME uncomment once all deps are vendored
-    ("src/tools/cargo", EXCEPTIONS_CARGO, None),
+    ("src/tools/cargo", EXCEPTIONS_CARGO, None, false),
     //("src/tools/miri/test-cargo-miri", &[], None), // FIXME uncomment once all deps are vendored
     //("src/tools/miri/test_dependencies", &[], None), // FIXME uncomment once all deps are vendored
-    ("src/tools/rust-analyzer", EXCEPTIONS_RUST_ANALYZER, None),
-    ("src/tools/rustc-perf", EXCEPTIONS_RUSTC_PERF, None),
-    ("src/tools/x", &[], None),
+    ("src/tools/rust-analyzer", EXCEPTIONS_RUST_ANALYZER, None, false),
+    ("src/tools/rustc-perf", EXCEPTIONS_RUSTC_PERF, None, true),
+    ("src/tools/x", &[], None, false),
     // tidy-alphabetical-end
 ];
 
@@ -514,7 +523,18 @@ const PERMITTED_CRANELIFT_DEPENDENCIES: &[&str] = &[
 pub fn check(root: &Path, cargo: &Path, bad: &mut bool) {
     let mut checked_runtime_licenses = false;
 
-    for &(workspace, exceptions, permitted_deps) in WORKSPACES {
+    for &(workspace, exceptions, permitted_deps, is_submodule) in WORKSPACES {
+        // Skip if it's a submodule, not in a CI environment, and not initialized.
+        //
+        // This prevents enforcing developers to fetch submodules for tidy.
+        if is_submodule
+            && !CiEnv::is_ci()
+            // If the directory is empty, we can consider it as an uninitialized submodule.
+            && read_dir(root.join(workspace)).unwrap().next().is_none()
+        {
+            continue;
+        }
+
         if !root.join(workspace).join("Cargo.lock").exists() {
             tidy_error!(bad, "the `{workspace}` workspace doesn't have a Cargo.lock");
             continue;
diff --git a/src/tools/tidy/src/extdeps.rs b/src/tools/tidy/src/extdeps.rs
index 2118de5f20411..3e0e2a58b7d92 100644
--- a/src/tools/tidy/src/extdeps.rs
+++ b/src/tools/tidy/src/extdeps.rs
@@ -1,6 +1,7 @@
 //! Check for external package sources. Allow only vendorable packages.
 
-use std::fs;
+use build_helper::ci::CiEnv;
+use std::fs::{self, read_dir};
 use std::path::Path;
 
 /// List of allowed sources for packages.
@@ -13,7 +14,18 @@ const ALLOWED_SOURCES: &[&str] = &[
 /// Checks for external package sources. `root` is the path to the directory that contains the
 /// workspace `Cargo.toml`.
 pub fn check(root: &Path, bad: &mut bool) {
-    for &(workspace, _, _) in crate::deps::WORKSPACES {
+    for &(workspace, _, _, is_submodule) in crate::deps::WORKSPACES {
+        // Skip if it's a submodule, not in a CI environment, and not initialized.
+        //
+        // This prevents enforcing developers to fetch submodules for tidy.
+        if is_submodule
+            && !CiEnv::is_ci()
+            // If the directory is empty, we can consider it as an uninitialized submodule.
+            && read_dir(root.join(workspace)).unwrap().next().is_none()
+        {
+            continue;
+        }
+
         // FIXME check other workspaces too
         // `Cargo.lock` of rust.
         let path = root.join(workspace).join("Cargo.lock");