diff --git a/llvm/include/llvm/CodeGen/TargetInstrInfo.h b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
--- a/llvm/include/llvm/CodeGen/TargetInstrInfo.h
+++ b/llvm/include/llvm/CodeGen/TargetInstrInfo.h
@@ -1937,6 +1937,10 @@
     return Formatter.get();
   }
 
+  /// Returns the target-specific default value for tail duplication.
+  /// This value will be used if the tail-dup-size argument is not provided.
+  virtual unsigned getTailDuplicateSizeOverride() const { return 2; }
+
 private:
   mutable std::unique_ptr<MIRFormatter> Formatter;
   unsigned CallFrameSetupOpcode, CallFrameDestroyOpcode;
diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -564,12 +564,17 @@
   // duplicate only one, because one branch instruction can be eliminated to
   // compensate for the duplication.
   unsigned MaxDuplicateCount;
+
   bool OptForSize = MF->getFunction().hasOptSize() ||
                     llvm::shouldOptimizeForSize(&TailBB, PSI, MBFI);
-  if (TailDupSize == 0)
-    MaxDuplicateCount = TailDuplicateSize;
-  else
+  if (TailDupSize == 0) {
+    if (TailDuplicateSize.getNumOccurrences() > 0)
+      MaxDuplicateCount = TailDuplicateSize;
+    else
+      MaxDuplicateCount = TII->getTailDuplicateSizeOverride();
+  } else
     MaxDuplicateCount = TailDupSize;
+
   if (OptForSize)
     MaxDuplicateCount = 1;