diff --git a/CHANGELOG.md b/CHANGELOG.md
index f837958ae..740194aad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,6 +34,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Revset/template aliases now support function overloading.
   [#2966](https://github.com/martinvonz/jj/issues/2966)
 
+* Conflicted files are individually simplified before being materialized.
+
 ### Fixed bugs
 
 ## [0.18.0] - 2024-06-05
diff --git a/cli/tests/test_resolve_command.rs b/cli/tests/test_resolve_command.rs
index 297605c1b..086bc92cd 100644
--- a/cli/tests/test_resolve_command.rs
+++ b/cli/tests/test_resolve_command.rs
@@ -516,38 +516,36 @@ fn test_simplify_conflict_sides() {
         &[],
     );
 
+    // Even though the tree-level conflict is a 4-sided conflict, each file is
+    // materialized as a 2-sided conflict.
+    insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["debug", "tree"]),
+    @r###"
+    fileA: Ok(Conflicted([Some(File { id: FileId("d00491fd7e5bb6fa28c517a0bb32b8b506539d4d"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("0cfbf08886fca9a91cb753ec8734c84fcbe52c9f"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false })]))
+    fileB: Ok(Conflicted([Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("d00491fd7e5bb6fa28c517a0bb32b8b506539d4d"), executable: false }), Some(File { id: FileId("df967b96a579e45a18b8251732d16804b2e56a55"), executable: false }), Some(File { id: FileId("0cfbf08886fca9a91cb753ec8734c84fcbe52c9f"), executable: false })]))
+    "###);
     // TODO: The conflict should be simplified before being displayed.
     insta::assert_snapshot!(test_env.jj_cmd_success(&repo_path, &["resolve", "--list"]),
     @r###"
     fileA    4-sided conflict
     fileB    4-sided conflict
     "###);
-    // TODO: The conflict should be simplified before being materialized.
     insta::assert_snapshot!(
     std::fs::read_to_string(repo_path.join("fileA")).unwrap(), @r###"
     <<<<<<< Conflict 1 of 1
-    %%%%%%% Changes from base #1 to side #1
+    %%%%%%% Changes from base to side #1
     -base
     +1
     +++++++ Contents of side #2
     2
-    %%%%%%% Changes from base #2 to side #3
-     base
-    %%%%%%% Changes from base #3 to side #4
-     base
     >>>>>>> Conflict 1 of 1 ends
     "###);
     insta::assert_snapshot!(
     std::fs::read_to_string(repo_path.join("fileB")).unwrap(), @r###"
     <<<<<<< Conflict 1 of 1
-    %%%%%%% Changes from base #1 to side #1
-     base
-    %%%%%%% Changes from base #2 to side #2
-     base
-    %%%%%%% Changes from base #3 to side #3
+    %%%%%%% Changes from base to side #1
     -base
     +1
-    +++++++ Contents of side #4
+    +++++++ Contents of side #2
     2
     >>>>>>> Conflict 1 of 1 ends
     "###);
diff --git a/lib/src/conflicts.rs b/lib/src/conflicts.rs
index 6bc9bcee7..83754a3b4 100644
--- a/lib/src/conflicts.rs
+++ b/lib/src/conflicts.rs
@@ -114,6 +114,7 @@ pub async fn materialize(
     output: &mut dyn Write,
 ) -> std::io::Result<()> {
     if let Some(file_merge) = conflict.to_file_merge() {
+        let file_merge = file_merge.simplify();
         let content = extract_as_single_hunk(&file_merge, store, path).await;
         materialize_merge_result(&content, output)
     } else {
diff --git a/lib/tests/test_local_working_copy.rs b/lib/tests/test_local_working_copy.rs
index 8d2de2d28..fe81decf4 100644
--- a/lib/tests/test_local_working_copy.rs
+++ b/lib/tests/test_local_working_copy.rs
@@ -639,28 +639,28 @@ fn test_materialize_conflicted_files() {
         }
     );
 
-    // TODO: Materialized conflicted file should be simplified.
+    // Even though the tree-level conflict is a 3-sided conflict, each file is
+    // materialized as a 2-sided conflict.
+    let file1_value = merged_tree.path_value(file1_path).unwrap();
+    let file2_value = merged_tree.path_value(file2_path).unwrap();
+    assert_eq!(file1_value.num_sides(), 3);
+    assert_eq!(file2_value.num_sides(), 3);
     insta::assert_snapshot!(std::fs::read_to_string(file1_path.to_fs_path(&workspace_root)).ok().unwrap(), @r###"
     <<<<<<< Conflict 1 of 1
-    %%%%%%% Changes from base #1 to side #1
-     a
-    %%%%%%% Changes from base #2 to side #2
+    %%%%%%% Changes from base to side #1
     -b
     +a
-    +++++++ Contents of side #3
+    +++++++ Contents of side #2
     c
     >>>>>>> Conflict 1 of 1 ends
     "###);
-    // TODO: Materialized conflicted file should be simplified.
     insta::assert_snapshot!(std::fs::read_to_string(file2_path.to_fs_path(&workspace_root)).ok().unwrap(), @r###"
     <<<<<<< Conflict 1 of 1
-    %%%%%%% Changes from base #1 to side #1
+    %%%%%%% Changes from base to side #1
     -2
     +1
     +++++++ Contents of side #2
     4
-    %%%%%%% Changes from base #2 to side #3
-     3
     >>>>>>> Conflict 1 of 1 ends
     "###);
 }