diff --git a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/ConcurrentTests.cs b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/ConcurrentTests.cs
index 1f8ed5777074f3..88c9f4b30b83b4 100644
--- a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/ConcurrentTests.cs
+++ b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/ConcurrentTests.cs
@@ -163,7 +163,7 @@ private static BufferBlock<int> ConstructBufferNewWithNMessages(int messagesCoun
         {
             var block = new BufferBlock<int>();
             block.PostRange(0, messagesCount);
-            SpinWait.SpinUntil(() => block.Count == messagesCount); // spin until messages available
+            Assert.True(SpinWait.SpinUntil(() => block.Count == messagesCount, DataflowTestHelpers.SpinTimeoutMs)); // spin until messages available
             return block;
         }
 
@@ -171,7 +171,7 @@ private static TransformBlock<int, string> ConstructTransformWithNMessages(int m
         {
             var block = new TransformBlock<int, string>(i => i.ToString());
             block.PostRange(0, messagesCount);
-            SpinWait.SpinUntil(() => block.OutputCount == messagesCount);
+            Assert.True(SpinWait.SpinUntil(() => block.OutputCount == messagesCount, DataflowTestHelpers.SpinTimeoutMs));
             return block;
         }
 
@@ -179,7 +179,7 @@ private static TransformManyBlock<int, int> ConstructTransformManyWithNMessages(
         {
             var block = new TransformManyBlock<int, int>(i => new int[] { i });
             block.PostRange(0, messagesCount);
-            SpinWait.SpinUntil(() => block.OutputCount == messagesCount); // spin until messages available
+            Assert.True(SpinWait.SpinUntil(() => block.OutputCount == messagesCount, DataflowTestHelpers.SpinTimeoutMs)); // spin until messages available
             return block;
         }
 
@@ -187,7 +187,7 @@ private static BatchBlock<int> ConstructBatchNewWithNMessages(int messagesCount)
         {
             var block = new BatchBlock<int>(1);
             block.PostRange(0, messagesCount);
-            SpinWait.SpinUntil(() => block.OutputCount == messagesCount); // spin until messages available
+            Assert.True(SpinWait.SpinUntil(() => block.OutputCount == messagesCount, DataflowTestHelpers.SpinTimeoutMs)); // spin until messages available
             return block;
         }
 
@@ -199,7 +199,7 @@ private static BatchedJoinBlock<int, int> ConstructBatchedJoin2NewWithNMessages(
                 block.Target1.Post(i);
                 block.Target2.Post(i);
             }
-            SpinWait.SpinUntil(() => block.OutputCount == messagesCount); // spin until messages available
+            Assert.True(SpinWait.SpinUntil(() => block.OutputCount == messagesCount, DataflowTestHelpers.SpinTimeoutMs)); // spin until messages available
             return block;
         }
 
@@ -223,7 +223,7 @@ private static JoinBlock<int, int> ConstructJoinNewWithNMessages(int messagesCou
             var block = new JoinBlock<int, int>();
             block.Target1.PostRange(0, messagesCount);
             block.Target2.PostRange(0, messagesCount);
-            SpinWait.SpinUntil(() => block.OutputCount == messagesCount); // spin until messages available
+            Assert.True(SpinWait.SpinUntil(() => block.OutputCount == messagesCount, DataflowTestHelpers.SpinTimeoutMs)); // spin until messages available
             return block;
         }
 
diff --git a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/DataflowTestHelper.cs b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/DataflowTestHelper.cs
index 3dbabb20246d74..8679d3908bb071 100644
--- a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/DataflowTestHelper.cs
+++ b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/DataflowTestHelper.cs
@@ -12,6 +12,9 @@ internal static partial class DataflowTestHelpers
         internal static bool[] BooleanValues = { true, false };
         internal static Func<int, IEnumerable<int>> ToEnumerable = item => Enumerable.Repeat(item, 1);
 
+        /// <summary>Timeout in milliseconds for spin-wait operations in tests, to avoid indefinite hangs under stress.</summary>
+        internal const int SpinTimeoutMs = 30_000;
+
         internal static ITargetBlock<int> PostRange(this ITargetBlock<int> target, int lowerBoundInclusive, int upperBoundExclusive)
         {
             return PostRange(target, lowerBoundInclusive, upperBoundExclusive, i => i);
diff --git a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformBlockTests.cs b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformBlockTests.cs
index 069abcee3c745c..6934cc51bb52cf 100644
--- a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformBlockTests.cs
+++ b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformBlockTests.cs
@@ -324,7 +324,7 @@ public async Task TestCount()
             Assert.Equal(expected: 0, actual: tb.OutputCount);
 
             tb.PostRange(1, 11);
-            await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10));
+            Assert.True(await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10, DataflowTestHelpers.SpinTimeoutMs)));
             for (int i = 10; i > 0; i--)
             {
                 int item;
diff --git a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.IAsyncEnumerable.cs b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.IAsyncEnumerable.cs
index 73205b6057341f..f92413c804bb7c 100644
--- a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.IAsyncEnumerable.cs
+++ b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.IAsyncEnumerable.cs
@@ -339,7 +339,7 @@ public async Task TestCountAsyncEnumerable()
             Assert.Equal(expected: 0, actual: tb.OutputCount);
 
             tb.PostRange(1, 11);
-            await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10));
+            Assert.True(await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10, DataflowTestHelpers.SpinTimeoutMs)));
             for (int i = 10; i > 0; i--)
             {
                 Assert.True(tb.TryReceive(out int item));
diff --git a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.cs b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.cs
index 53e4bf816a4d40..6f32a0d246fbeb 100644
--- a/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.cs
+++ b/src/libraries/System.Threading.Tasks.Dataflow/tests/Dataflow/TransformManyBlockTests.cs
@@ -352,7 +352,7 @@ public async Task TestCount()
             Assert.Equal(expected: 0, actual: tb.OutputCount);
 
             tb.PostRange(1, 11);
-            await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10));
+            Assert.True(await Task.Run(() => SpinWait.SpinUntil(() => tb.OutputCount == 10, DataflowTestHelpers.SpinTimeoutMs)));
             for (int i = 10; i > 0; i--)
             {
                 int item;