Index: llvm/trunk/include/llvm/ProfileData/Coverage/CoverageMapping.h
===================================================================
--- llvm/trunk/include/llvm/ProfileData/Coverage/CoverageMapping.h
+++ llvm/trunk/include/llvm/ProfileData/Coverage/CoverageMapping.h
@@ -245,12 +245,6 @@
     return std::pair<unsigned, unsigned>(LineEnd, ColumnEnd);
   }
 
-  bool operator<(const CounterMappingRegion &Other) const {
-    if (FileID != Other.FileID)
-      return FileID < Other.FileID;
-    return startLoc() < Other.startLoc();
-  }
-
   bool contains(const CounterMappingRegion &Other) const {
     if (FileID != Other.FileID)
       return false;
Index: llvm/trunk/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
===================================================================
--- llvm/trunk/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
+++ llvm/trunk/lib/ProfileData/Coverage/CoverageMappingWriter.cpp
@@ -108,8 +108,16 @@
 
 void CoverageMappingWriter::write(raw_ostream &OS) {
   // Sort the regions in an ascending order by the file id and the starting
-  // location.
-  std::stable_sort(MappingRegions.begin(), MappingRegions.end());
+  // location. Sort by region kinds to ensure stable order for tests.
+  std::stable_sort(
+      MappingRegions.begin(), MappingRegions.end(),
+      [](const CounterMappingRegion &LHS, const CounterMappingRegion &RHS) {
+        if (LHS.FileID != RHS.FileID)
+          return LHS.FileID < RHS.FileID;
+        if (LHS.startLoc() != RHS.startLoc())
+          return LHS.startLoc() < RHS.startLoc();
+        return LHS.Kind < RHS.Kind;
+      });
 
   // Write out the fileid -> filename mapping.
   encodeULEB128(VirtualFileMapping.size(), OS);