diff --git a/Cargo.toml b/Cargo.toml
index 5c4b0839..527f3828 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "swc_sourcemap"
-version = "9.3.1"
+version = "9.3.2"
 authors = ["Sentry <hello@sentry.io>", "swc-project <https://swc.rs>"]
 keywords = ["javascript", "sourcemap", "sourcemaps"]
 description = "Forked from https://github.com/getsentry/rust-sourcemap"
diff --git a/src/lazy/mod.rs b/src/lazy/mod.rs
index 26b52f3d..1b235c61 100644
--- a/src/lazy/mod.rs
+++ b/src/lazy/mod.rs
@@ -132,19 +132,41 @@ where
     }
 }
 
+impl<'a, T> MaybeRawValue<'a, T>
+where
+    T: Deserialize<'a>,
+    T: Default,
+{
+    pub fn as_data(&mut self) -> &mut T {
+        match self {
+            MaybeRawValue::RawValue(s) => {
+                *self = MaybeRawValue::Data(
+                    serde_json::from_str(s.get()).expect("Failed to convert RawValue to Data"),
+                );
+                if let MaybeRawValue::Data(data) = self {
+                    data
+                } else {
+                    unreachable!()
+                }
+            }
+            MaybeRawValue::Data(data) => data,
+        }
+    }
+}
+
 type Str = BytesStr;
 
 type StrValue<'a> = MaybeRawValue<'a, Str>;
 
 #[derive(Debug)]
 pub struct SourceMap<'a> {
-    file: Option<StrValue<'a>>,
-    tokens: Vec<RawToken>,
-    names: MaybeRawValue<'a, Vec<StrValue<'a>>>,
-    source_root: Option<StrValue<'a>>,
-    sources: MaybeRawValue<'a, Vec<StrValue<'a>>>,
-    sources_content: MaybeRawValue<'a, Vec<Option<StrValue<'a>>>>,
-    ignore_list: Option<MaybeRawValue<'a, BTreeSet<u32>>>,
+    pub(crate) file: Option<StrValue<'a>>,
+    pub(crate) tokens: Vec<RawToken>,
+    pub(crate) names: MaybeRawValue<'a, Vec<StrValue<'a>>>,
+    pub(crate) source_root: Option<StrValue<'a>>,
+    pub(crate) sources: MaybeRawValue<'a, Vec<StrValue<'a>>>,
+    pub(crate) sources_content: MaybeRawValue<'a, Vec<Option<StrValue<'a>>>>,
+    pub(crate) ignore_list: Option<MaybeRawValue<'a, BTreeSet<u32>>>,
 }
 
 #[derive(Debug)]
@@ -444,6 +466,35 @@ impl<'a> SourceMap<'a> {
             ignore_list: self.ignore_list,
         }
     }
+
+    pub fn file(&mut self) -> Option<&BytesStr> {
+        self.file.as_mut().map(|f| &*f.as_data())
+    }
+
+    pub fn sources(&mut self) -> impl Iterator<Item = &'_ BytesStr> + use<'_, 'a> {
+        self.sources.as_data().iter_mut().map(|d| &*d.as_data())
+    }
+
+    pub fn get_source(&mut self, src_id: u32) -> Option<&BytesStr> {
+        self.sources
+            .as_data()
+            .get_mut(src_id as usize)
+            .map(|d| &*d.as_data())
+    }
+
+    pub fn get_name(&mut self, src_id: u32) -> Option<&BytesStr> {
+        self.names
+            .as_data()
+            .get_mut(src_id as usize)
+            .map(|d| &*d.as_data())
+    }
+
+    pub fn get_source_contents(&mut self, src_id: u32) -> Option<&BytesStr> {
+        self.sources_content
+            .as_data()
+            .get_mut(src_id as usize)
+            .and_then(|d| d.as_mut().map(|d| &*d.as_data()))
+    }
 }
 
 impl<'a> SourceMapIndex<'a> {
diff --git a/src/types.rs b/src/types.rs
index f1100902..0580a6d6 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -15,6 +15,7 @@ use crate::utils::{find_common_prefix, greatest_lower_bound};
 
 use bytes_str::BytesStr;
 use debugid::DebugId;
+use rustc_hash::FxHashSet;
 
 /// Controls the `SourceMap::rewrite` behavior
 ///
@@ -940,6 +941,14 @@ impl SourceMap {
             Cow::Borrowed(&adjustment.tokens),
         );
     }
+
+    /// Perform a similar operation as [`Self::adjust_mappings`], but by rewriting the last
+    /// sourcemap as opposed to the input source map:
+    ///
+    /// `transform.js.map.adjust_mappings_from_multiple([foo.js.map, bar.js.map])`
+    pub fn adjust_mappings_from_multiple(self, adjustments: Vec<crate::lazy::SourceMap>) -> Self {
+        adjust_mappings_from_multiple(self, adjustments)
+    }
 }
 
 pub(crate) fn adjust_mappings(
@@ -1076,6 +1085,207 @@ pub(crate) fn adjust_mappings(
     new_tokens
 }
 
+pub fn adjust_mappings_from_multiple(
+    mut this: SourceMap,
+    mut input_maps: Vec<crate::lazy::SourceMap>,
+) -> SourceMap {
+    // Helper struct that makes it easier to compare tokens by the start and end
+    // of the range they cover.
+    #[derive(Debug, Clone, Copy)]
+    struct Range<'a> {
+        start: (u32, u32),
+        end: (u32, u32),
+        value: &'a RawToken,
+        map_idx: u32,
+    }
+
+    /// Turns a list of tokens into a list of ranges, using the provided `key` function to determine the order of the tokens.
+    #[allow(clippy::ptr_arg)]
+    fn create_ranges(
+        tokens: &mut [(u32, RawToken)],
+        key: fn(&RawToken) -> (u32, u32),
+    ) -> Vec<Range<'_>> {
+        tokens.sort_unstable_by_key(|(_, t)| key(t));
+
+        let mut token_iter = tokens.iter().peekable();
+        let mut ranges = Vec::new();
+
+        while let Some((map_idx, t)) = token_iter.next() {
+            let start = key(t);
+            let next_start = token_iter
+                .peek()
+                .map_or((u32::MAX, u32::MAX), |(_, t)| key(t));
+            // A token extends either to the start of the next token or the end of the line, whichever comes sooner
+            let end = std::cmp::min(next_start, (start.0, u32::MAX));
+            ranges.push(Range {
+                start,
+                end,
+                value: t,
+                map_idx: *map_idx,
+            });
+        }
+
+        ranges
+    }
+
+    // Turn `self.tokens` and `adjustment.tokens` into vectors of ranges so we have easy access to
+    // both start and end.
+    // We want to compare `self` and `adjustment` tokens by line/column numbers in the "original source" file.
+    // These line/column numbers are the `dst_line/col` for
+    // the `self` tokens and `src_line/col` for the `adjustment` tokens.
+    let mut input_tokens = input_maps
+        .iter_mut()
+        .enumerate()
+        .flat_map(|(i, map)| {
+            std::mem::take(&mut map.tokens)
+                .into_iter()
+                .map(move |t| ((i + 1) as u32, t))
+        })
+        .collect::<Vec<_>>();
+    let input_ranges = create_ranges(&mut input_tokens[..], |t| (t.dst_line, t.dst_col));
+    let mut self_tokens = std::mem::take(&mut this.tokens)
+        .into_iter()
+        .map(|t| (0u32, t))
+        .collect::<Vec<_>>();
+    let self_ranges = create_ranges(&mut self_tokens[..], |t| (t.src_line, t.src_col));
+
+    let mut input_ranges_iter = input_ranges.iter();
+    let mut input_range = match input_ranges_iter.next() {
+        Some(r) => Some(r),
+        None => return this,
+    };
+
+    let covered_input_files = input_maps
+        .iter_mut()
+        .flat_map(|m| m.file().cloned())
+        .collect::<FxHashSet<_>>();
+
+    let mut new_map = SourceMapBuilder::new(None);
+    let mut add_mapping = |input_maps: &mut Vec<crate::lazy::SourceMap<'_>>,
+                           map_idx: u32,
+                           dst_line: u32,
+                           dst_col: u32,
+                           src_line: u32,
+                           src_col: u32,
+                           src_id: u32,
+                           name_id: u32,
+                           is_range: bool| {
+        let (src_id, name) = if map_idx == 0 {
+            let src = this.get_source(src_id).cloned();
+            (
+                src.map(|src| {
+                    let src_id = new_map.add_source(src);
+                    new_map.set_source_contents(src_id, this.get_source_contents(src_id).cloned());
+                    src_id
+                }),
+                this.get_name(name_id).cloned(),
+            )
+        } else {
+            let this = &mut input_maps[(map_idx - 1) as usize];
+            let src = this.get_source(src_id).cloned();
+            (
+                src.map(|src| {
+                    let src_id = new_map.add_source(src);
+                    new_map.set_source_contents(src_id, this.get_source_contents(src_id).cloned());
+                    src_id
+                }),
+                this.get_name(name_id).cloned(),
+            )
+        };
+        let name_id = name.map(|name| new_map.add_source(name));
+        new_map.add_raw(
+            dst_line, dst_col, src_line, src_col, src_id, name_id, is_range,
+        );
+    };
+
+    // Iterate over `self_ranges` (sorted by `src_line/col`). For each such range, consider
+    // all `self_ranges` which overlap with it.
+    for &self_range in &self_ranges {
+        // The `self_range` offsets lines and columns by a certain amount. All `input_ranges`
+        // it covers will get the same offset.
+        let (line_diff, col_diff) = (
+            self_range.value.dst_line as i32 - self_range.value.src_line as i32,
+            self_range.value.dst_col as i32 - self_range.value.src_col as i32,
+        );
+
+        // Skip `input_ranges` that are entirely before the `_range`.
+        while input_range.is_some_and(|input_range| input_range.end <= self_range.start) {
+            input_range = input_ranges_iter.next();
+        }
+        // At this point `self_range.end` > `input_range.start`
+
+        if input_range.is_none_or(|input_range| {
+            self_range.start >= input_range.end
+                || this.get_source(self_range.value.src_id).is_none_or(|src| {
+                    Some(src) != input_maps[(input_range.map_idx - 1) as usize].file()
+                })
+        }) {
+            // No input range matches this range, keep the mapping though if this file isn't covered
+            // by any input sourcemap
+            if this
+                .get_source(self_range.value.src_id)
+                .is_none_or(|f| !covered_input_files.contains(f))
+            {
+                add_mapping(
+                    &mut input_maps,
+                    0,
+                    self_range.value.dst_line,
+                    self_range.value.dst_col,
+                    self_range.value.src_line,
+                    self_range.value.src_col,
+                    self_range.value.src_id,
+                    self_range.value.name_id,
+                    self_range.value.is_range,
+                );
+            }
+        } else {
+            let mut input_range_value = input_range.unwrap();
+            // Iterate over `input_range` that fall at least partially within the `self_ranges`.
+            while input_range_value.start < self_range.end {
+                // If `input_range` started before `self_range`, cut off the token's start.
+                let (dst_line, dst_col) = std::cmp::max(input_range_value.start, self_range.start);
+                add_mapping(
+                    &mut input_maps,
+                    input_range_value.map_idx,
+                    (dst_line as i32 + line_diff) as u32,
+                    (dst_col as i32 + col_diff) as u32,
+                    input_range_value.value.src_line,
+                    input_range_value.value.src_col,
+                    input_range_value.value.src_id,
+                    input_range_value.value.name_id,
+                    input_range_value.value.is_range,
+                );
+
+                if input_range_value.end >= self_range.end {
+                    // There are surely no more `input_ranges` for this `self_range`.
+                    // Break the loop without advancing the `input_range`.
+                    break;
+                } else {
+                    //  Advance the `input_range`.
+                    match input_ranges_iter.next() {
+                        Some(r) => {
+                            input_range_value = r;
+                            input_range = Some(r);
+                        }
+                        None => {
+                            input_range = None;
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    let mut new_map = new_map.into_sourcemap();
+
+    new_map
+        .tokens
+        .sort_unstable_by_key(|t| (t.dst_line, t.dst_col));
+
+    new_map
+}
+
 impl SourceMapIndex {
     /// Creates a sourcemap index from a reader over a JSON stream in UTF-8
     /// format.  Optionally a "garbage header" as defined by the
@@ -1420,6 +1630,8 @@ impl SourceMapSection {
 mod tests {
     use std::collections::BTreeSet;
 
+    use crate::lazy::MaybeRawValue;
+
     use super::{DecodedMap, RewriteOptions, SourceMap, SourceMapIndex, SourceMapSection};
     use debugid::DebugId;
 
@@ -1507,6 +1719,43 @@ mod tests {
         }
     }
 
+    #[test]
+    fn adjust_mappings_from_multiple() {
+        let original_map_file = std::fs::read_to_string(
+            "tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js.map",
+        )
+        .unwrap();
+
+        let bundled_map_file =
+            std::fs::read_to_string("tests/fixtures/adjust_mappings_from_multiple/bundle.js.map")
+                .unwrap();
+
+        let mut original_map = crate::lazy::decode(original_map_file.as_bytes())
+            .unwrap()
+            .into_source_map()
+            .unwrap();
+        original_map.file = Some(MaybeRawValue::Data("turbopack:///[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.js".into()));
+
+        let bundled_map = match crate::decode(bundled_map_file.as_bytes()).unwrap() {
+            DecodedMap::Regular(source_map) => source_map,
+            DecodedMap::Index(source_map_index) => source_map_index.flatten().unwrap(),
+            DecodedMap::Hermes(_) => unimplemented!(),
+        };
+        // original_map.adjust_mappings(&bundled_map);
+        let bundled_map = bundled_map.adjust_mappings_from_multiple(vec![original_map]);
+
+        let mut result = vec![];
+        bundled_map.to_writer(&mut result).unwrap();
+        let result = String::from_utf8(result).unwrap();
+        // std::fs::write("tests/fixtures/adjust_mappings_from_multiple/merged.js.map", result).unwrap();
+
+        let bundled_map_file =
+            std::fs::read_to_string("tests/fixtures/adjust_mappings_from_multiple/merged.js.map")
+                .unwrap();
+
+        assert_eq!(bundled_map_file, result)
+    }
+
     #[test]
     fn test_roundtrip() {
         let sm = br#"{
diff --git a/tests/fixtures/adjust_mappings_from_multiple/bundle.js b/tests/fixtures/adjust_mappings_from_multiple/bundle.js
new file mode 100644
index 00000000..ccaa1f8f
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/bundle.js
@@ -0,0 +1,20 @@
+(globalThis.TURBOPACK = globalThis.TURBOPACK || []).push(["output/4c35f_tests_snapshot_source_maps_input-source-map-merged_input_index_e9baadb1.js", {
+
+"[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/index.js [test] (ecmascript)": [((__turbopack_context__) => {
+"use strict";
+
+// MERGED MODULE: [project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/index.js [test] (ecmascript)
+;
+__turbopack_context__.s({}, "[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/index.js [test] (ecmascript)");
+// MERGED MODULE: [project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.js [test] (ecmascript)
+;
+function runExternalSourceMapped(fn) {
+    return fn();
+} //# sourceMappingURL=sourcemapped.js.map
+;
+runExternalSourceMapped();
+}), ["[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.js [test] (ecmascript)"]]
+,
+}]);
+
+//# sourceMappingURL=4c35f_tests_snapshot_source_maps_input-source-map-merged_input_index_e9baadb1.js.map
\ No newline at end of file
diff --git a/tests/fixtures/adjust_mappings_from_multiple/bundle.js.map b/tests/fixtures/adjust_mappings_from_multiple/bundle.js.map
new file mode 100644
index 00000000..eeaae2e5
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/bundle.js.map
@@ -0,0 +1,25 @@
+{
+  "version": 3,
+  "sources": [],
+  "sections": [
+    {
+      "offset": {
+        "line": 5,
+        "column": 0
+      },
+      "map": {
+        "version": 3,
+        "sources": [
+          "turbopack:///[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.js",
+          "turbopack:///[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/index.js"
+        ],
+        "sourcesContent": [
+          "export function runExternalSourceMapped(fn) {\n    return fn();\n}\n//# sourceMappingURL=sourcemapped.js.map",
+          "import { runExternalSourceMapped } from './sourcemapped.js'\n\nrunExternalSourceMapped()\n"
+        ],
+        "names": [],
+        "mappings": ";;;;;AAAO,SAAS,wBAAwB,EAAE;IACtC,OAAO;AACX,EACA,wCAAwC;;ACDxC"
+      }
+    }
+  ]
+}
diff --git a/tests/fixtures/adjust_mappings_from_multiple/merged.js.map b/tests/fixtures/adjust_mappings_from_multiple/merged.js.map
new file mode 100644
index 00000000..cb30ac8a
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/merged.js.map
@@ -0,0 +1 @@
+{"version":3,"sources":["sourcemapped.ts","turbopack:///[project]/turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/index.js"],"sourcesContent":["// Compile with pnpm tsc turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.ts --sourceMap --inlineSources --target esnext\n// tsc compile errors can be ignored\ntype Fn<T> = () => T\nexport function runExternalSourceMapped<T>(fn: Fn<T>): T {\n  return fn()\n}\n","import { runExternalSourceMapped } from './sourcemapped.js'\n\nrunExternalSourceMapped()\n"],"names":[],"mappings":";;;;;;;;;;AAGM,SAAU,uBAAuB,CAAI,EAAS;IAClD,OAAO,EAAE,EAAE,CAAA;;;ACFb"}
\ No newline at end of file
diff --git a/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js
new file mode 100644
index 00000000..da8a4fd3
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js
@@ -0,0 +1,4 @@
+export function runExternalSourceMapped(fn) {
+    return fn();
+}
+//# sourceMappingURL=sourcemapped.js.map
\ No newline at end of file
diff --git a/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js.map b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js.map
new file mode 100644
index 00000000..3a41042b
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.js.map
@@ -0,0 +1 @@
+{"version":3,"file":"sourcemapped.js","sourceRoot":"","sources":["sourcemapped.ts"],"names":[],"mappings":"AAGA,MAAM,UAAU,uBAAuB,CAAI,EAAS;IAClD,OAAO,EAAE,EAAE,CAAA;AACb,CAAC","sourcesContent":["// Compile with pnpm tsc turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.ts --sourceMap --inlineSources --target esnext\n// tsc compile errors can be ignored\ntype Fn<T> = () => T\nexport function runExternalSourceMapped<T>(fn: Fn<T>): T {\n  return fn()\n}\n"]}
\ No newline at end of file
diff --git a/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.ts b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.ts
new file mode 100644
index 00000000..409bc830
--- /dev/null
+++ b/tests/fixtures/adjust_mappings_from_multiple/sourcemapped.ts
@@ -0,0 +1,6 @@
+// Compile with pnpm tsc turbopack/crates/turbopack-tests/tests/snapshot/source_maps/input-source-map-merged/input/sourcemapped.ts --sourceMap --inlineSources --target esnext
+// tsc compile errors can be ignored
+type Fn<T> = () => T
+export function runExternalSourceMapped<T>(fn: Fn<T>): T {
+  return fn()
+}