diff --git a/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs b/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs
index b0a4ab2522064..35e0095aa9fc5 100644
--- a/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs
+++ b/src/Compilers/CSharp/Test/Emit2/Semantics/CollectionExpressionTests.cs
@@ -28975,7 +28975,7 @@ public void M()
             comp.VerifyEmitDiagnostics();
         }
 
-        [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/70381")]
+        [ConditionalFact(typeof(WindowsOrLinuxOnly)), WorkItem("https://github.com/dotnet/roslyn/issues/70381")]
         public void ExtremelyNestedCollectionExpressionDoesNotOverflow_1()
         {
             var code = $$"""
diff --git a/src/Compilers/CSharp/Test/EndToEnd/EndToEndTests.cs b/src/Compilers/CSharp/Test/EndToEnd/EndToEndTests.cs
index d6e0431585ae3..ccc34c3e368d9 100644
--- a/src/Compilers/CSharp/Test/EndToEnd/EndToEndTests.cs
+++ b/src/Compilers/CSharp/Test/EndToEnd/EndToEndTests.cs
@@ -18,6 +18,7 @@
 using System.Threading;
 using System.Diagnostics;
 using Roslyn.Test.Utilities.TestGenerators;
+using System.Runtime.InteropServices;
 
 namespace Microsoft.CodeAnalysis.CSharp.UnitTests.EndToEnd
 {
@@ -174,14 +175,15 @@ void M2() {
         [Fact, WorkItem("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1874763")]
         public void OverflowOnFluentCall_ExtensionMethods()
         {
-            int numberFluentCalls = (IntPtr.Size, ExecutionConditionUtil.Configuration, RuntimeUtilities.IsDesktopRuntime) switch
-            {
-                (8, ExecutionConfiguration.Debug, false) => 750,
-                (8, ExecutionConfiguration.Release, false) => 750, // Should be ~3_400, but is flaky.
-                (4, ExecutionConfiguration.Debug, true) => 450,
-                (4, ExecutionConfiguration.Release, true) => 1_600,
-                (8, ExecutionConfiguration.Debug, true) => 1_100,
-                (8, ExecutionConfiguration.Release, true) => 3_300,
+            int numberFluentCalls = (IntPtr.Size, ExecutionConditionUtil.Configuration, RuntimeUtilities.IsDesktopRuntime, RuntimeInformation.IsOSPlatform(OSPlatform.OSX)) switch
+            {
+                (8, ExecutionConfiguration.Debug, false, false) => 750,
+                (8, ExecutionConfiguration.Release, false, false) => 750, // Should be ~3_400, but is flaky.
+                (4, ExecutionConfiguration.Debug, true, false) => 450,
+                (4, ExecutionConfiguration.Release, true, false) => 1_600,
+                (8, ExecutionConfiguration.Debug, true, false) => 1_100,
+                (8, ExecutionConfiguration.Release, true, false) => 3_300,
+                (_, _, _, true) => 200,
                 _ => throw new Exception($"Unexpected configuration {IntPtr.Size * 8}-bit {ExecutionConditionUtil.Configuration}, Desktop: {RuntimeUtilities.IsDesktopRuntime}")
             };
 
diff --git a/src/Tools/Source/RunTests/TestRunner.cs b/src/Tools/Source/RunTests/TestRunner.cs
index cedf33d604544..f837f34a2e8d9 100644
--- a/src/Tools/Source/RunTests/TestRunner.cs
+++ b/src/Tools/Source/RunTests/TestRunner.cs
@@ -193,6 +193,7 @@ string MakeHelixWorkItemProject(WorkItemInfo workItemInfo)
                 // We could relax this and allow for example Linux clients to kick off Windows jobs, but we'd have to
                 // figure out solutions for issues such as creating file paths in the correct format for the target machine.
                 var isUnix = !RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+                var isMac = RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
 
                 var setEnvironmentVariable = isUnix ? "export" : "set";
 
@@ -202,15 +203,40 @@ string MakeHelixWorkItemProject(WorkItemInfo workItemInfo)
                 command.AppendLine(isUnix ? $"ls -l" : $"dir");
                 command.AppendLine("dotnet --info");
 
-                var knownEnvironmentVariables = new[] { "ROSLYN_TEST_IOPERATION", "ROSLYN_TEST_USEDASSEMBLIES" };
+                string[] knownEnvironmentVariables =
+                [
+                    "ROSLYN_TEST_IOPERATION",
+                    "ROSLYN_TEST_USEDASSEMBLIES"
+                ];
+
                 foreach (var knownEnvironmentVariable in knownEnvironmentVariables)
                 {
-                    if (string.Equals(Environment.GetEnvironmentVariable(knownEnvironmentVariable), "true", StringComparison.OrdinalIgnoreCase))
+                    if (Environment.GetEnvironmentVariable(knownEnvironmentVariable) is string { Length: > 0 } value)
                     {
-                        command.AppendLine($"{setEnvironmentVariable} {knownEnvironmentVariable}=true");
+                        command.AppendLine($"{setEnvironmentVariable} {knownEnvironmentVariable}=\"{value}\"");
                     }
                 }
 
+                // OSX produces extremely large dump files that commonly exceed the limits of Helix 
+                // uploads. These settings limit the dump file size + produce a .json detailing crash 
+                // reasons that work better with Helix size limitations.
+                if (isMac)
+                {
+                    command.AppendLine($"{setEnvironmentVariable} DOTNET_DbgEnableMiniDump=1");
+                    command.AppendLine($"{setEnvironmentVariable} DOTNET_DbgMiniDumpType=1");
+                    command.AppendLine($"{setEnvironmentVariable} DOTNET_EnableCrashReport=1");
+                }
+
+                // Set the dump folder so that dotnet writes all dump files to this location automatically. 
+                // This saves the need to scan for all the different types of dump files later and copy
+                // them around.
+                var helixDumpFolder = isUnix
+                    ? @"$HELIX_DUMP_FOLDER/crash.%d.%e.dmp"
+                    : @"%HELIX_DUMP_FOLDER%\crash.%d.%e.dmp";
+                command.AppendLine($"{setEnvironmentVariable} DOTNET_DbgMiniDumpName=\"{helixDumpFolder}\"");
+
+                command.AppendLine(isUnix ? "env | sort" : "set");
+
                 // Create a payload directory that contains all the assemblies in the work item in separate folders.
                 var payloadDirectory = Path.Combine(msbuildTestPayloadRoot, "artifacts", "bin");
 
@@ -259,6 +285,9 @@ string MakeHelixWorkItemProject(WorkItemInfo workItemInfo)
                 // return value of the main command is captured; a Helix Job is considered to fail if the main command returns a
                 // non-zero error code, and we don't want the cleanup steps to interefere with that. PostCommands exist
                 // precisely to address this problem.
+                //
+                // This is still necessary even with us setting  DOTNET_DbgMiniDumpName because the system can create 
+                // non .NET Core dump files that aren't controlled by that value.
                 var postCommands = new StringBuilder();
 
                 if (isUnix)