diff --git a/SingleSource/UnitTests/Vectorizer/common.h b/SingleSource/UnitTests/Vectorizer/common.h
index fc7b850400a5..cd376c52144b 100644
--- a/SingleSource/UnitTests/Vectorizer/common.h
+++ b/SingleSource/UnitTests/Vectorizer/common.h
@@ -84,6 +84,14 @@
     }                                                                          \
   };
 
+#define DEFINE_SCALAR_AND_VECTOR_FN4_PTR(Loop)                                 \
+  auto ScalarFn = [](auto *FirstA, auto *LastA, auto *FirstB, auto *LastB) {   \
+    _Pragma("clang loop vectorize(disable) interleave_count(1)") Loop          \
+  };                                                                           \
+  auto VectorFn = [](auto *FirstA, auto *LastA, auto *FirstB, auto *LastB) {   \
+    _Pragma("clang loop vectorize(enable)") Loop                               \
+  };
+
 static std::mt19937 rng;
 
 // Initialize arrays A with random numbers.
diff --git a/SingleSource/UnitTests/Vectorizer/find-first-of.cpp b/SingleSource/UnitTests/Vectorizer/find-first-of.cpp
new file mode 100644
index 000000000000..e634a232c816
--- /dev/null
+++ b/SingleSource/UnitTests/Vectorizer/find-first-of.cpp
@@ -0,0 +1,195 @@
+
+#include <functional>
+#include <iostream>
+#include <limits>
+#include <memory>
+#include <stdint.h>
+
+#include "common.h"
+
+template <typename Ty>
+using Fn2Ty = std::function<Ty *(Ty *, Ty *, Ty *, Ty *)>;
+template <typename Ty>
+static void checkVectorFunction(Fn2Ty<Ty> ScalarFn, Fn2Ty<Ty> VectorFn,
+                                const char *Name) {
+  std::cout << "Checking " << Name << "\n";
+
+  const unsigned A_n = 1000;
+  const unsigned B_n = 64;
+  std::unique_ptr<Ty[]> A(new Ty[A_n]);
+  std::unique_ptr<Ty[]> B(new Ty[B_n]);
+  init_data(A, A_n);
+  init_data(B, B_n);
+
+  // Test VectorFn with different input data.
+  {
+    // Check with random inputs.
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check with A < B for all elements.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check with no match -> should return sentinel.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check with all matching -> should return first element.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::min();
+    }
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check with only first element of A matching first element of B.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    A[0] = B[0] = std::numeric_limits<Ty>::min() + 1;
+
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check with only first element of A matching last element of B.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    A[0] = B[B_n - 1] = std::numeric_limits<Ty>::min() + 1;
+
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check multiple matches, first at index 7.
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    A[7] = B[0] = std::numeric_limits<Ty>::min() + 1;
+    A[19] = B[37] = std::numeric_limits<Ty>::min() + 2;
+    A[450] = B[52] = std::numeric_limits<Ty>::min() + 3;
+
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+
+  {
+    // Check multiple matches, first at A[0] matching B[N-1], second at A[1]
+    // matching B[0].
+    for (unsigned i = 0; i < A_n; ++i) {
+      A[i] = std::numeric_limits<Ty>::min();
+    }
+    for (unsigned i = 0; i < B_n; ++i) {
+      B[i] = std::numeric_limits<Ty>::max();
+    }
+    A[0] = B[B_n - 1] = std::numeric_limits<Ty>::min() + 1;
+    A[1] = B[0] = std::numeric_limits<Ty>::min() + 2;
+
+    auto Reference = ScalarFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    auto ToCheck = VectorFn(A.get(), A.get() + A_n, B.get(), B.get() + B_n);
+    if (Reference != ToCheck) {
+      std::cerr << "Miscompare\n";
+      exit(1);
+    }
+  }
+}
+
+int main() {
+  rng = std::mt19937(15);
+
+#define DEFINE_FIND_FIRST_OF_LOOP                                              \
+  for (; FirstA != LastA; ++FirstA)                                            \
+    for (auto *It = FirstB; It != LastB; ++It)                                 \
+      if (*FirstA == *It)                                                      \
+        return FirstA;                                                         \
+  return LastA;
+
+  {
+    DEFINE_SCALAR_AND_VECTOR_FN4_PTR(DEFINE_FIND_FIRST_OF_LOOP);
+
+    checkVectorFunction<uint8_t>(ScalarFn, VectorFn, "find_first_of_u8");
+  }
+
+  {
+    DEFINE_SCALAR_AND_VECTOR_FN4_PTR(DEFINE_FIND_FIRST_OF_LOOP);
+
+    checkVectorFunction<uint16_t>(ScalarFn, VectorFn, "find_first_of_u16");
+  }
+
+  {
+    DEFINE_SCALAR_AND_VECTOR_FN4_PTR(DEFINE_FIND_FIRST_OF_LOOP);
+
+    checkVectorFunction<uint32_t>(ScalarFn, VectorFn, "find_first_of_u32");
+  }
+
+  {
+    DEFINE_SCALAR_AND_VECTOR_FN4_PTR(DEFINE_FIND_FIRST_OF_LOOP);
+
+    checkVectorFunction<uint64_t>(ScalarFn, VectorFn, "find_first_of_u64");
+  }
+
+  return 0;
+}
diff --git a/SingleSource/UnitTests/Vectorizer/find-first-of.reference_output b/SingleSource/UnitTests/Vectorizer/find-first-of.reference_output
new file mode 100644
index 000000000000..adb8992ff4c2
--- /dev/null
+++ b/SingleSource/UnitTests/Vectorizer/find-first-of.reference_output
@@ -0,0 +1,5 @@
+Checking find_first_of_u8
+Checking find_first_of_u16
+Checking find_first_of_u32
+Checking find_first_of_u64
+exit 0