Index: lld/MachO/OutputSegment.cpp
===================================================================
--- lld/MachO/OutputSegment.cpp
+++ lld/MachO/OutputSegment.cpp
@@ -140,10 +140,13 @@
 }
 
 void OutputSegment::sortOutputSections() {
-  llvm::sort(sections, compareByOrder<OutputSection *>(sectionOrder));
+  llvm::stable_sort(sections, compareByOrder<OutputSection *>(sectionOrder));
 }
 
 void macho::sortOutputSegments() {
+  // sort() instead of stable_sort() is fine because segmentOrder() is
+  // name-based and getOrCreateOutputSegment() makes there's only a single
+  // segment for every name.
   llvm::sort(outputSegments, compareByOrder<OutputSegment *>(segmentOrder));
 }
 
Index: lld/MachO/Writer.cpp
===================================================================
--- lld/MachO/Writer.cpp
+++ lld/MachO/Writer.cpp
@@ -78,7 +78,7 @@
 
   LCUuid *uuidCommand = nullptr;
   OutputSegment *linkEditSegment = nullptr;
-  DenseMap<NamePair, ConcatOutputSection *> concatOutputSections;
+  MapVector<NamePair, ConcatOutputSection *> concatOutputSections;
 };
 
 // LC_DYLD_INFO_ONLY stores the offsets of symbol import/export information.