diff --git a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/StringTests.cs b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/StringTests.cs
index 4ec41acad8c125..1f7df0d8f4012a 100644
--- a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/StringTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/StringTests.cs
@@ -1134,6 +1134,7 @@ public void Replace_NoSuchStringComparison_ThrowsArgumentException(StringCompari
         }
 
 
+        [UnconditionalSuppressMessage("AOT", "IL3050", Justification = "Test field used only in conditional tests.")]
         private static readonly StringComparison[] StringComparisons = (StringComparison[])Enum.GetValues(typeof(StringComparison));
 
         [Fact]
@@ -1244,6 +1245,7 @@ public static void GetHashCode_NoSuchStringComparison_ThrowsArgumentException(St
         [Theory]
         [InlineData("")] // empty string
         [InlineData("hello")] // non-empty string
+        [UnconditionalSuppressMessage("AOT", "IL3050", Justification = "DynamicMethod usage is guarded by IsReflectionEmitSupported runtime check.")]
         public static unsafe void GetPinnableReference_ReturnsSameAsGCHandleAndLegacyFixed(string input)
         {
             Assert.NotNull(input); // test shouldn't have null input
@@ -1303,6 +1305,7 @@ public static unsafe void GetPinnableReference_ReturnsSameAsGCHandleAndLegacyFix
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsReflectionEmitSupported))]
+        [UnconditionalSuppressMessage("AOT", "IL3050", Justification = "Test is skipped when reflection emit is not supported.")]
         public static unsafe void GetPinnableReference_WithNullInput_ThrowsNullRef()
         {
             // This test uses an explicit call instead of the normal callvirt that C# would emit.
diff --git a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/TimeZoneInfoTests.cs b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/TimeZoneInfoTests.cs
index 0067c38562b376..5651efc143224d 100644
--- a/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/TimeZoneInfoTests.cs
+++ b/src/libraries/System.Runtime/tests/System.Runtime.Tests/System/TimeZoneInfoTests.cs
@@ -2172,6 +2172,8 @@ public static void ToSerializedString_FromSerializedString_RoundTrips(TimeZoneIn
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsBinaryFormatterSupported))]
         [MemberData(nameof(SystemTimeZonesTestData))]
+        [UnconditionalSuppressMessage("Trimming", "IL2026", Justification = "Test is skipped when BinaryFormatter is not supported.")]
+        [UnconditionalSuppressMessage("AOT", "IL3050", Justification = "Test is skipped when BinaryFormatter is not supported.")]
         public static void BinaryFormatter_RoundTrips(TimeZoneInfo timeZone)
         {
             BinaryFormatter formatter = new BinaryFormatter();
@@ -2187,6 +2189,7 @@ public static void BinaryFormatter_RoundTrips(TimeZoneInfo timeZone)
         }
 
         [Fact]
+        [UnconditionalSuppressMessage("Trimming", "IL2075", Justification = "Test uses reflection to inspect internal properties for diagnostics.")]
         public static void TimeZoneInfo_DoesConvertTimeForOldDatesOfTimeZonesWithExceedingMaxRange()
         {
             // On some OSes this time zone contains old adjustment rules which have offset higher than 14h