diff --git a/unittests/Support/BlockFrequencyTest.cpp b/unittests/Support/BlockFrequencyTest.cpp
new file mode 100644
index 0000000..edeea9b
--- /dev/null
+++ b/unittests/Support/BlockFrequencyTest.cpp
@@ -0,0 +1,56 @@
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/BlockFrequency.h"
+#include "llvm/Support/BranchProbability.h"
+
+#include "gtest/gtest.h"
+#include <climits>
+
+using namespace llvm;
+
+namespace {
+
+TEST(BlockFrequencyTest, OneToZero) {
+  BlockFrequency Freq(1);
+  BranchProbability Prob(UINT32_MAX - 1, UINT32_MAX);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), 0u);
+}
+
+TEST(BlockFrequencyTest, OneToOne) {
+  BlockFrequency Freq(1);
+  BranchProbability Prob(UINT32_MAX, UINT32_MAX);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), 1u);
+}
+
+TEST(BlockFrequencyTest, ThreeToOne) {
+  BlockFrequency Freq(3);
+  BranchProbability Prob(3000000, 9000000);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), 1u);
+}
+
+TEST(BlockFrequencyTest, MaxToHalfMax) {
+  BlockFrequency Freq(UINT64_MAX);
+  BranchProbability Prob(UINT32_MAX / 2, UINT32_MAX);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), 9223372034707292159LLu);
+}
+
+TEST(BlockFrequencyTest, BigToBig) {
+  const uint64_t Big = 387246523487234346LL;
+  const uint32_t P = 123456789;
+  BlockFrequency Freq(Big);
+  BranchProbability Prob(P, P);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), Big);
+}
+
+TEST(BlockFrequencyTest, MaxToMax) {
+  BlockFrequency Freq(UINT64_MAX);
+  BranchProbability Prob(UINT32_MAX, UINT32_MAX);
+  Freq *= Prob;
+  EXPECT_EQ(Freq.getFrequency(), UINT64_MAX);
+}
+
+}