diff --git a/clang/unittests/StaticAnalyzer/RangeSetTest.cpp b/clang/unittests/StaticAnalyzer/RangeSetTest.cpp
--- a/clang/unittests/StaticAnalyzer/RangeSetTest.cpp
+++ b/clang/unittests/StaticAnalyzer/RangeSetTest.cpp
@@ -88,6 +88,12 @@
   template <typename Base>
   static constexpr T X555TruncZeroOf = TruncZeroOf<X555, Base>; // 0x5555'5600
 
+// Silence 'warning C4309: 'initializing': truncation of constant value'
+//   in RangeSetCastToPromotionConversionTest.
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(push)
+#pragma warning(disable : 4309)
+#endif
   // Numbers for ranges with the same bits in the lowest byte.
   // 0xAAAA'AA2A
   static constexpr T FromA = ClearLowBytes<XAAA, sizeof(T) - 1> + 42;
@@ -95,6 +101,10 @@
   // 0x5555'552A
   static constexpr T FromB = ClearLowBytes<X555, sizeof(T) - 1> + 42;
   static constexpr T ToB = FromB + 2; // 0x5555'552C
+
+#if defined(_MSC_VER) && !defined(__clang__)
+#pragma warning(pop)
+#endif
 };
 
 template <typename T>