diff --git a/tests/xharness/Harness.cs b/tests/xharness/Harness.cs
index 30c401a314..e8275fbbcb 100644
--- a/tests/xharness/Harness.cs
+++ b/tests/xharness/Harness.cs
@@ -82,6 +82,7 @@ namespace xharness
 		public string JENKINS_RESULTS_DIRECTORY { get; set; } // Use same name as in Makefiles, so that a grep finds it.
 		public string MAC_DESTDIR { get; set; }
 		public string IOS_DESTDIR { get; set; }
+		public bool IncludeMac32 { get; set; }
 
 		// Run
 		public AppRunnerTarget Target { get; set; }
diff --git a/tests/xharness/MacClassicTarget.cs b/tests/xharness/MacClassicTarget.cs
index 797998dcce..01ad629328 100644
--- a/tests/xharness/MacClassicTarget.cs
+++ b/tests/xharness/MacClassicTarget.cs
@@ -4,6 +4,11 @@ namespace xharness
 {
 	public class MacClassicTarget : MacTarget
 	{
+		public MacClassicTarget ()
+		{
+			ThirtyTwoBit = true;
+		}
+
 		protected override void ExecuteInternal ()
 		{
 			// nothing to do here
diff --git a/tests/xharness/MacTarget.cs b/tests/xharness/MacTarget.cs
index aed5244cd5..769c64abbb 100644
--- a/tests/xharness/MacTarget.cs
+++ b/tests/xharness/MacTarget.cs
@@ -4,6 +4,8 @@ namespace xharness
 {
 	public class MacTarget : Target
 	{
+		public bool ThirtyTwoBit;
+
 		protected override bool FixProjectReference (string name)
 		{
 			switch (name) {
diff --git a/tests/xharness/MacUnifiedTarget.cs b/tests/xharness/MacUnifiedTarget.cs
index 31c23e8702..0f6b4c995d 100644
--- a/tests/xharness/MacUnifiedTarget.cs
+++ b/tests/xharness/MacUnifiedTarget.cs
@@ -12,7 +12,6 @@ namespace xharness
 		bool IsBCL => BCLInfo != null;
 
 		bool SkipProjectGeneration;
-		bool ThirtyTwoBit;
 		bool SkipSuffix;
 
 		public MacUnifiedTarget (bool mobile, bool thirtyTwoBit, bool shouldSkipProjectGeneration = false, bool skipSuffix = false) : base ()
diff --git a/tests/xharness/MakefileGenerator.cs b/tests/xharness/MakefileGenerator.cs
index d2e9a492c2..2e0796e1ba 100644
--- a/tests/xharness/MakefileGenerator.cs
+++ b/tests/xharness/MakefileGenerator.cs
@@ -194,7 +194,11 @@ namespace xharness
 				writer.WriteLine ("# Container targets that run multiple test projects");
 				writer.WriteLine ();
 
-				var grouped = allTargets.GroupBy ((target) => target.SimplifiedName);
+				IEnumerable<MacTarget> groupableTargets = allTargets;
+				if (!harness.IncludeMac32)
+					groupableTargets = groupableTargets.Where ((v) => !v.ThirtyTwoBit);
+
+				var grouped = groupableTargets.GroupBy ((target) => target.SimplifiedName);
 				foreach (MacTargetNameType action in Enum.GetValues (typeof (MacTargetNameType))) {
 					var actionName = action.ToString ().ToLowerInvariant ();
 					foreach (var group in grouped) {
@@ -210,7 +214,7 @@ namespace xharness
 
 				writer.WriteLine ("mac-run run-mac:");
 				writer.WriteLine ("\t$(Q) rm -rf \".$@-failure.stamp\"");
-				foreach (var target in allTargets) {
+				foreach (var target in groupableTargets) {
 					if (target is MacClassicTarget)
 						writer.WriteLine ("\t$(Q) $(MAKE) {0} || echo \"{0} failed\" >> \".$@-failure.stamp\"", MakeMacClassicTargetName (target, MacTargetNameType.Run));
 					else if (target is MacUnifiedTarget)
@@ -224,7 +228,7 @@ namespace xharness
 
 				writer.WriteLine ("mac-build mac-build-all build-mac:"); // build everything
 				writer.WriteLine ("\t$(Q) rm -rf \".$@-failure.stamp\"");
-				foreach (var target in allTargets) {
+				foreach (var target in groupableTargets) {
 					if (target is MacClassicTarget)
 						writer.WriteLine ("\t$(Q) $(MAKE) {0} || echo \"{0} failed\" >> \".$@-failure.stamp\"", MakeMacClassicTargetName (target, MacTargetNameType.Build));
 					else if (target is MacUnifiedTarget)