diff --git a/compiler/rustc_session/src/config.rs b/compiler/rustc_session/src/config.rs
index 297df7c2c9765..5180162ae47d6 100644
--- a/compiler/rustc_session/src/config.rs
+++ b/compiler/rustc_session/src/config.rs
@@ -1207,13 +1207,26 @@ fn maybe_strip_file_name(mut path: PathBuf) -> PathBuf {
     if path.file_name().map_or(0, |name| name.len()) > MAX_FILENAME_LENGTH {
         let filename = path.file_name().unwrap().to_string_lossy();
         let hash_len = 64 / 4; // Hash64 is 64 bits encoded in hex
-        let stripped_len = filename.len() - MAX_FILENAME_LENGTH + hash_len;
+        let hyphen_len = 1; // the '-' we insert between hash and suffix
+
+        // number of bytes of suffix we can keep so that "hash-<suffix>" fits
+        let allowed_suffix = MAX_FILENAME_LENGTH.saturating_sub(hash_len + hyphen_len);
+
+        // number of bytes to remove from the start
+        let stripped_bytes = filename.len().saturating_sub(allowed_suffix);
+
+        // Find the next character boundary at or after `stripped_bytes` so slicing is valid.
+        let split_at = filename
+            .char_indices()
+            .find(|(i, _)| *i >= stripped_bytes)
+            .map(|(i, _)| i)
+            .unwrap_or(filename.len());
 
         let mut hasher = StableHasher::new();
-        filename[..stripped_len].hash(&mut hasher);
+        filename[..split_at].hash(&mut hasher);
         let hash = hasher.finish::<Hash64>();
 
-        path.set_file_name(format!("{:x}-{}", hash, &filename[stripped_len..]));
+        path.set_file_name(format!("{:x}-{}", hash, &filename[split_at..]));
     }
     path
 }
diff --git a/tests/run-make/lto-long-filenames/rmake.rs b/tests/run-make/lto-long-filenames/rmake.rs
index 9e0ba63e9f5b8..98ce54e5efc82 100644
--- a/tests/run-make/lto-long-filenames/rmake.rs
+++ b/tests/run-make/lto-long-filenames/rmake.rs
@@ -9,8 +9,6 @@
 
 //@ ignore-cross-compile
 
-use std::fs;
-
 use run_make_support::{rfs, rustc};
 
 // This test make sure we don't get such following error:
diff --git a/tests/run-make/lto-long-filenames_cn/rmake.rs b/tests/run-make/lto-long-filenames_cn/rmake.rs
new file mode 100644
index 0000000000000..f129b686012dc
--- /dev/null
+++ b/tests/run-make/lto-long-filenames_cn/rmake.rs
@@ -0,0 +1,19 @@
+//@ ignore-cross-compile
+
+use run_make_support::{rfs, rustc};
+
+// This test make sure we don't crash when lto creates output files with long names.
+// cn characters can be multi-byte and thus trigger the long filename reduction code more easily.
+// we need to make sure that the code is properly generating names at char boundaries.
+// as reported in issue #147975
+fn main() {
+    let lto_flags = ["-Clto", "-Clto=yes", "-Clto=off", "-Clto=thin", "-Clto=fat"];
+    for prefix_len in 0..4 {
+        let prefix: String = std::iter::repeat("_").take(prefix_len).collect();
+        let main_file = format!("{}28_找出字符串中第一个匹配项的下标.rs", prefix);
+        rfs::write(&main_file, "fn main() {}\n");
+        for flag in lto_flags {
+            rustc().input(&main_file).arg(flag).run();
+        }
+    }
+}