diff --git a/changelogs/unreleased/25931-gitlab-merge-request-view-crash-when-commiting-a-js-sourcemap-file.yml b/changelogs/unreleased/25931-gitlab-merge-request-view-crash-when-commiting-a-js-sourcemap-file.yml
new file mode 100644
index 0000000000000000000000000000000000000000..023ec1abcfa401b6d68742d65c57228eb2118841
--- /dev/null
+++ b/changelogs/unreleased/25931-gitlab-merge-request-view-crash-when-commiting-a-js-sourcemap-file.yml
@@ -0,0 +1,4 @@
+---
+title: Fix timeout when MR contains large files marked as binary by .gitattributes
+merge_request:
+author:
diff --git a/lib/gitlab/diff/file_collection/merge_request_diff.rb b/lib/gitlab/diff/file_collection/merge_request_diff.rb
index 56530448f3603475b68161bf684d40a8df20f9ea..329d12f13d161210356d1d6342c01b2ca77b85c1 100644
--- a/lib/gitlab/diff/file_collection/merge_request_diff.rb
+++ b/lib/gitlab/diff/file_collection/merge_request_diff.rb
@@ -61,7 +61,10 @@ module Gitlab
         end
 
         def cacheable?(diff_file)
-          @merge_request_diff.present? && diff_file.blob && diff_file.blob.text?
+          @merge_request_diff.present? &&
+            diff_file.blob &&
+            diff_file.blob.text? &&
+            @project.repository.diffable?(diff_file.blob)
         end
 
         def cache_key
diff --git a/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb b/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
index 2a680f03476acbeeacee02ef9f5c63db323cfd28..f2bc15d39d7a19e8016ce6607d461da36600c3cd 100644
--- a/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
+++ b/spec/lib/gitlab/diff/file_collection/merge_request_diff_spec.rb
@@ -1,21 +1,30 @@
 require 'spec_helper'
 
 describe Gitlab::Diff::FileCollection::MergeRequestDiff do
-  let(:merge_request) { create :merge_request }
+  let(:merge_request) { create(:merge_request) }
+  let(:diff_files) { described_class.new(merge_request.merge_request_diff, diff_options: nil).diff_files }
 
-  it 'does not hightlight binary files' do
+  it 'does not highlight binary files' do
     allow_any_instance_of(Gitlab::Diff::File).to receive(:blob).and_return(double("text?" => false))
 
     expect_any_instance_of(Gitlab::Diff::File).not_to receive(:highlighted_diff_lines)
 
-    described_class.new(merge_request.merge_request_diff, diff_options: nil).diff_files
+    diff_files
   end
 
-  it 'does not hightlight file if blob is not accessable' do
+  it 'does not highlight file if blob is not accessable' do
     allow_any_instance_of(Gitlab::Diff::File).to receive(:blob).and_return(nil)
 
     expect_any_instance_of(Gitlab::Diff::File).not_to receive(:highlighted_diff_lines)
 
-    described_class.new(merge_request.merge_request_diff, diff_options: nil).diff_files
+    diff_files
+  end
+
+  it 'does not files marked as undiffable in .gitattributes' do
+    allow_any_instance_of(Repository).to receive(:diffable?).and_return(false)
+
+    expect_any_instance_of(Gitlab::Diff::File).not_to receive(:highlighted_diff_lines)
+
+    diff_files
   end
 end
diff --git a/spec/services/merge_requests/merge_request_diff_cache_service_spec.rb b/spec/services/merge_requests/merge_request_diff_cache_service_spec.rb
index 05cdbe5287a4dbf4b7349a277e7036de8ea31551..35804d41b4605446de979e4e91459df3239493f0 100644
--- a/spec/services/merge_requests/merge_request_diff_cache_service_spec.rb
+++ b/spec/services/merge_requests/merge_request_diff_cache_service_spec.rb
@@ -11,6 +11,7 @@ describe MergeRequests::MergeRequestDiffCacheService do
       expect(Rails.cache).to receive(:read).with(cache_key).and_return({})
       expect(Rails.cache).to receive(:write).with(cache_key, anything)
       allow_any_instance_of(Gitlab::Diff::File).to receive(:blob).and_return(double("text?" => true))
+      allow_any_instance_of(Repository).to receive(:diffable?).and_return(true)
 
       subject.execute(merge_request)
     end