Index: MicroBenchmarks/LoopVectorization/RuntimeChecks.cpp
===================================================================
--- MicroBenchmarks/LoopVectorization/RuntimeChecks.cpp
+++ MicroBenchmarks/LoopVectorization/RuntimeChecks.cpp
@@ -4,6 +4,8 @@
 
 #include "benchmark/benchmark.h"
 
+#define ITERATIONS 1000000000
+
 static std::mt19937 rng;
 
 // Initialize array A with random numbers.
@@ -126,3 +128,22 @@
   }
 }
 BENCHMARK(benchVecWithRuntimeChecks4PointersDAfterA)->Arg(32)->Arg(1000);
+
+// Convert each vector element from T to int8_t in a vectorized loop
+template <typename T> static void vecWithRuntimeChecksofTruncVecInLoop(T *A, const uint8_t *B, int iterations) {
+  for (unsigned i = 0; i < iterations; i++) {
+    A[i] += B[i];
+  }
+}
+
+void benchVecWithRuntimeChecksofTruncVeci64InLoop(benchmark::State &state) {
+  std::unique_ptr<uint64_t[]> A(new uint64_t[ITERATIONS]);
+  std::unique_ptr<uint8_t[]> B(new uint8_t[ITERATIONS]);
+  init_data(A, ITERATIONS);
+  init_data(B, ITERATIONS);
+  vecWithRuntimeChecksofTruncVecInLoop(&A[0], &B[0], ITERATIONS);
+  benchmark::DoNotOptimize(A);
+  benchmark::DoNotOptimize(B);
+  benchmark::ClobberMemory();
+}
+BENCHMARK(benchVecWithRuntimeChecksofTruncVeci64InLoop);