diff --git a/llvm/include/llvm/CodeGen/MachineTraceMetrics.h b/llvm/include/llvm/CodeGen/MachineTraceMetrics.h
--- a/llvm/include/llvm/CodeGen/MachineTraceMetrics.h
+++ b/llvm/include/llvm/CodeGen/MachineTraceMetrics.h
@@ -82,6 +82,12 @@
   LiveRegUnit(unsigned RU) : RegUnit(RU) {}
 };
 
+/// Strategies for selecting traces.
+enum class MachineTraceStrategy {
+  /// Select the trace through a block that has the fewest instructions.
+  TS_MinInstrCount,
+  TS_NumStrategies
+};
 
 class MachineTraceMetrics : public MachineFunctionPass {
   const MachineFunction *MF = nullptr;
@@ -372,18 +378,10 @@
 
   };
 
-  /// Strategies for selecting traces.
-  enum Strategy {
-    /// Select the trace through a block that has the fewest instructions.
-    TS_MinInstrCount,
-
-    TS_NumStrategies
-  };
-
   /// Get the trace ensemble representing the given trace selection strategy.
   /// The returned Ensemble object is owned by the MachineTraceMetrics analysis,
   /// and valid for the lifetime of the analysis pass.
-  Ensemble *getEnsemble(Strategy);
+  Ensemble *getEnsemble(MachineTraceStrategy);
 
   /// Invalidate cached information about MBB. This must be called *before* MBB
   /// is erased, or the CFG is otherwise changed.
@@ -407,7 +405,8 @@
   SmallVector<unsigned, 0> ProcResourceCycles;
 
   // One ensemble per strategy.
-  Ensemble* Ensembles[TS_NumStrategies];
+  Ensemble
+      *Ensembles[static_cast<size_t>(MachineTraceStrategy::TS_NumStrategies)];
 
   // Convert scaled resource usage to a cycle count that can be compared with
   // latencies.
diff --git a/llvm/lib/CodeGen/EarlyIfConversion.cpp b/llvm/lib/CodeGen/EarlyIfConversion.cpp
--- a/llvm/lib/CodeGen/EarlyIfConversion.cpp
+++ b/llvm/lib/CodeGen/EarlyIfConversion.cpp
@@ -874,7 +874,7 @@
     return true;
 
   if (!MinInstr)
-    MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount);
+    MinInstr = Traces->getEnsemble(MachineTraceStrategy::TS_MinInstrCount);
 
   MachineTraceMetrics::Trace TBBTrace = MinInstr->getTrace(IfConv.getTPred());
   MachineTraceMetrics::Trace FBBTrace = MinInstr->getTrace(IfConv.getFPred());
diff --git a/llvm/lib/CodeGen/MachineCombiner.cpp b/llvm/lib/CodeGen/MachineCombiner.cpp
--- a/llvm/lib/CodeGen/MachineCombiner.cpp
+++ b/llvm/lib/CodeGen/MachineCombiner.cpp
@@ -575,7 +575,7 @@
   // Check if the block is in a loop.
   const MachineLoop *ML = MLI->getLoopFor(MBB);
   if (!MinInstr)
-    MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount);
+    MinInstr = Traces->getEnsemble(MachineTraceStrategy::TS_MinInstrCount);
 
   SparseSet<LiveRegUnit> RegUnits;
   RegUnits.setUniverse(TRI->getNumRegUnits());
diff --git a/llvm/lib/CodeGen/MachineTraceMetrics.cpp b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
--- a/llvm/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/llvm/lib/CodeGen/MachineTraceMetrics.cpp
@@ -380,15 +380,17 @@
 
 // Get an Ensemble sub-class for the requested trace strategy.
 MachineTraceMetrics::Ensemble *
-MachineTraceMetrics::getEnsemble(MachineTraceMetrics::Strategy strategy) {
-  assert(strategy < TS_NumStrategies && "Invalid trace strategy enum");
-  Ensemble *&E = Ensembles[strategy];
+MachineTraceMetrics::getEnsemble(MachineTraceStrategy strategy) {
+  assert(strategy < MachineTraceStrategy::TS_NumStrategies &&
+         "Invalid trace strategy enum");
+  Ensemble *&E = Ensembles[static_cast<size_t>(strategy)];
   if (E)
     return E;
 
   // Allocate new Ensemble on demand.
   switch (strategy) {
-  case TS_MinInstrCount: return (E = new MinInstrCountEnsemble(this));
+  case MachineTraceStrategy::TS_MinInstrCount:
+    return (E = new MinInstrCountEnsemble(this));
   default: llvm_unreachable("Invalid trace strategy enum");
   }
 }
diff --git a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
--- a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
@@ -855,7 +855,7 @@
   if (Stress)
     return true;
   if (!MinInstr)
-    MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount);
+    MinInstr = Traces->getEnsemble(MachineTraceStrategy::TS_MinInstrCount);
 
   // Head dominates CmpBB, so it is always included in its trace.
   MachineTraceMetrics::Trace Trace = MinInstr->getTrace(CmpConv.CmpBB);
diff --git a/llvm/lib/Target/AArch64/AArch64StorePairSuppress.cpp b/llvm/lib/Target/AArch64/AArch64StorePairSuppress.cpp
--- a/llvm/lib/Target/AArch64/AArch64StorePairSuppress.cpp
+++ b/llvm/lib/Target/AArch64/AArch64StorePairSuppress.cpp
@@ -75,7 +75,7 @@
 /// oversaturate the vector units.
 bool AArch64StorePairSuppress::shouldAddSTPToBlock(const MachineBasicBlock *BB) {
   if (!MinInstr)
-    MinInstr = Traces->getEnsemble(MachineTraceMetrics::TS_MinInstrCount);
+    MinInstr = Traces->getEnsemble(MachineTraceStrategy::TS_MinInstrCount);
 
   MachineTraceMetrics::Trace BBTrace = MinInstr->getTrace(BB);
   unsigned ResLength = BBTrace.getResourceLength();