diff --git a/src/package/nuspec/Microsoft.TestPlatform.TestHost.NetCore.props b/src/package/nuspec/Microsoft.TestPlatform.TestHost.NetCore.props
index fd9adc4d16..a33990d7a3 100644
--- a/src/package/nuspec/Microsoft.TestPlatform.TestHost.NetCore.props
+++ b/src/package/nuspec/Microsoft.TestPlatform.TestHost.NetCore.props
@@ -12,7 +12,7 @@
       <Visible>False</Visible>
     </Content>
   </ItemGroup>
-  <ItemGroup Condition=" '$(Platform)' == 'x64' AND '$(OS)' == 'Windows_NT'" >
+  <ItemGroup Condition=" '$(Platform)' != 'x86' AND '$(OS)' == 'Windows_NT'" >
     <Content Include="$(MSBuildThisFileDirectory)x64\testhost.exe">
       <Link>testhost.exe</Link>
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
diff --git a/src/vstest.console/CommandLine/InferHelper.cs b/src/vstest.console/CommandLine/InferHelper.cs
index f9dda8b734..1168cec2fb 100644
--- a/src/vstest.console/CommandLine/InferHelper.cs
+++ b/src/vstest.console/CommandLine/InferHelper.cs
@@ -27,9 +27,9 @@ internal InferHelper(IAssemblyMetadataProvider assemblyMetadataProvider)
         /// <summary>
         /// Determines Architecture from sources.
         /// </summary>
-        public Architecture AutoDetectArchitecture(List<string> sources, IDictionary<string, Architecture> sourcePlatforms)
+        public Architecture AutoDetectArchitecture(List<string> sources, IDictionary<string, Architecture> sourcePlatforms, Architecture defaultArchitecture)
         {
-            Architecture architecture = Constants.DefaultPlatform;
+            var architecture = defaultArchitecture;
             try
             {
                 if (sources != null && sources.Count > 0)
@@ -64,7 +64,7 @@ public Architecture AutoDetectArchitecture(List<string> sources, IDictionary<str
 
                         if (!finalArch.Equals(arch))
                         {
-                            finalArch = Constants.DefaultPlatform;
+                            finalArch = defaultArchitecture;
                             EqtTrace.Info("Conflict in platform architecture, using default platform:{0}", finalArch);
                         }
                     }
diff --git a/src/vstest.console/TestPlatformHelpers/TestRequestManager.cs b/src/vstest.console/TestPlatformHelpers/TestRequestManager.cs
index 3fcea2bf9b..05a81fbaf9 100644
--- a/src/vstest.console/TestPlatformHelpers/TestRequestManager.cs
+++ b/src/vstest.console/TestPlatformHelpers/TestRequestManager.cs
@@ -379,7 +379,13 @@ private bool UpdateRunSettingsIfRequired(string runsettingsXml, List<string> sou
                     var loggerRunSettings = XmlRunSettingsUtilities.GetLoggerRunSettings(runsettingsXml) ?? new LoggerRunSettings();
 
                     settingsUpdated |= this.UpdateFramework(document, navigator, sources, sourceFrameworks, registrar, out Framework chosenFramework);
-                    settingsUpdated |= this.UpdatePlatform(document, navigator, sources, sourcePlatforms, out Architecture chosenPlatform);
+
+                    // Choose default architecture based on the framework
+                    // For .NET core, the default platform architecture should be x64.
+                    var defaultArchitecture = chosenFramework.Name.IndexOf("netstandard", StringComparison.OrdinalIgnoreCase) >= 0
+                    || chosenFramework.Name.IndexOf("netcoreapp", StringComparison.OrdinalIgnoreCase) >= 0 ? Architecture.X64 : Architecture.X86; 
+
+                    settingsUpdated |= this.UpdatePlatform(document, navigator, sources, sourcePlatforms, defaultArchitecture, out Architecture chosenPlatform);
                     this.CheckSourcesForCompatibility(chosenFramework, chosenPlatform, sourcePlatforms, sourceFrameworks, registrar);
                     settingsUpdated |= this.UpdateDesignMode(document, runConfiguration);
                     settingsUpdated |= this.UpdateCollectSourceInformation(document, runConfiguration);
@@ -460,10 +466,10 @@ private void CheckSourcesForCompatibility(Framework chosenFramework, Architectur
             }
         }
 
-        private bool UpdatePlatform(XmlDocument document, XPathNavigator navigator, List<string> sources, IDictionary<string, Architecture> sourcePlatforms, out Architecture chosenPlatform)
+        private bool UpdatePlatform(XmlDocument document, XPathNavigator navigator, List<string> sources, IDictionary<string, Architecture> sourcePlatforms, Architecture defaultArchitecture, out Architecture chosenPlatform)
         {
             // Get platform from sources
-            var inferedPlatform = inferHelper.AutoDetectArchitecture(sources, sourcePlatforms);
+            var inferedPlatform = inferHelper.AutoDetectArchitecture(sources, sourcePlatforms, defaultArchitecture);
 
             // Get platform from runsettings
             bool updatePlatform = IsAutoPlatformDetectRequired(navigator, out chosenPlatform);
diff --git a/test/vstest.console.UnitTests/CommandLine/InferHelperTests.cs b/test/vstest.console.UnitTests/CommandLine/InferHelperTests.cs
index 4c35efddd4..900a5e2593 100644
--- a/test/vstest.console.UnitTests/CommandLine/InferHelperTests.cs
+++ b/test/vstest.console.UnitTests/CommandLine/InferHelperTests.cs
@@ -19,6 +19,7 @@ public class InferHelperTests
         private readonly Mock<IAssemblyMetadataProvider> mockAssemblyHelper;
         private InferHelper inferHelper;
         private readonly Framework defaultFramework = Framework.DefaultFramework;
+        private readonly Architecture DefaultArchitecture = Architecture.X64;
         private readonly Framework frameworkNet45 = Framework.FromString(".NETFramework,Version=4.5");
         private readonly Framework frameworkNet46 = Framework.FromString(".NETFramework,Version=4.6");
         private readonly Framework frameworkNet47 = Framework.FromString(".NETFramework,Version=4.7");
@@ -38,46 +39,46 @@ public InferHelperTests()
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnDefaultArchitectureOnNullSources()
         {
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(null, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(null, sourceArchitectures, DefaultArchitecture));
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnDefaultArchitectureOnEmptySources()
         {
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>(0), sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>(0), sourceArchitectures, DefaultArchitecture));
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnDefaultArchitectureOnNullItemInSources()
         {
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>(){null}, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>(){null}, sourceArchitectures, DefaultArchitecture));
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnDefaultArchitectureOnWhiteSpaceItemInSources()
         {
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { " "}, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { " "}, sourceArchitectures, DefaultArchitecture));
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnCorrectArchForOneSource()
         {
             this.mockAssemblyHelper.Setup(ah => ah.GetArchitecture(It.IsAny<string>())).Returns(Architecture.X86);
-            Assert.AreEqual(Architecture.X86, inferHelper.AutoDetectArchitecture(new List<string>(){"1.dll"}, sourceArchitectures));
+            Assert.AreEqual(Architecture.X86, inferHelper.AutoDetectArchitecture(new List<string>(){"1.dll"}, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()));
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldReturnCorrectDefaultArchForNotDotNetAssembly()
         {
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { "NotDotNetAssebly.appx" }, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { "NotDotNetAssebly.appx" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Never);
         }
 
         [TestMethod]
         public void AutoDetectArchitectureShouldSetAnyCpuArchForNotDotNetAssembly()
         {
-            inferHelper.AutoDetectArchitecture(new List<string>() { "NotDotNetAssebly.appx" }, sourceArchitectures);
+            inferHelper.AutoDetectArchitecture(new List<string>() { "NotDotNetAssebly.appx" }, sourceArchitectures, DefaultArchitecture);
             Assert.AreEqual(Architecture.AnyCPU, sourceArchitectures["NotDotNetAssebly.appx"]);
         }
 
@@ -86,7 +87,7 @@ public void AutoDetectArchitectureShouldReturnDefaultArchForAllAnyCpuAssemblies(
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU).Returns(Architecture.AnyCPU).Returns(Architecture.AnyCPU);
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "AnyCPU2.exe", "AnyCPU3.dll" }, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "AnyCPU2.exe", "AnyCPU3.dll" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(3));
         }
 
@@ -95,7 +96,7 @@ public void AutoDetectArchitectureShouldReturnX86ArchIfOneX86AssemblyAndRestAnyC
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU).Returns(Architecture.AnyCPU).Returns(Architecture.X86);
-            Assert.AreEqual(Architecture.X86, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "AnyCPU2.exe", "x86.dll" }, sourceArchitectures));
+            Assert.AreEqual(Architecture.X86, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "AnyCPU2.exe", "x86.dll" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(3));
         }
 
@@ -104,7 +105,7 @@ public void AutoDetectArchitectureShouldReturnARMArchIfOneARMAssemblyAndRestAnyC
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.ARM).Returns(Architecture.ARM).Returns(Architecture.ARM);
-            Assert.AreEqual(Architecture.ARM, inferHelper.AutoDetectArchitecture(new List<string>() { "ARM1.dll", "ARM2.dll", "ARM3.dll" }, sourceArchitectures));
+            Assert.AreEqual(Architecture.ARM, inferHelper.AutoDetectArchitecture(new List<string>() { "ARM1.dll", "ARM2.dll", "ARM3.dll" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(3));
         }
 
@@ -113,7 +114,7 @@ public void AutoDetectArchitectureShouldReturnX64ArchIfOneX64AssemblyAndRestAnyC
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU).Returns(Architecture.AnyCPU).Returns(Architecture.X64);
-            Assert.AreEqual(Architecture.X64, inferHelper.AutoDetectArchitecture(new List<string>() { "x64.dll", "AnyCPU2.exe", "x64.dll" }, sourceArchitectures));
+            Assert.AreEqual(Architecture.X64, inferHelper.AutoDetectArchitecture(new List<string>() { "x64.dll", "AnyCPU2.exe", "x64.dll" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(3));
         }
 
@@ -122,7 +123,7 @@ public void AutoDetectArchitectureShouldReturnDefaultArchOnConflictArches()
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU).Returns(Architecture.X64).Returns(Architecture.X86);
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "x64.exe", "x86.dll" }, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "x64.exe", "x86.dll" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(3));
         }
 
@@ -132,7 +133,7 @@ public void AutoDetectArchitectureShouldPoulateSourceArchitectureDictionary()
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU).Returns(Architecture.X64).Returns(Architecture.X86);
 
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "x64.exe", "x86.dll" }, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "x64.exe", "x86.dll" }, sourceArchitectures, DefaultArchitecture));
             Assert.AreEqual(3, sourceArchitectures.Count);
             Assert.AreEqual(Architecture.AnyCPU, sourceArchitectures["AnyCPU1.dll"]);
             Assert.AreEqual(Architecture.X64, sourceArchitectures["x64.exe"]);
@@ -146,7 +147,7 @@ public void AutoDetectArchitectureShouldReturnDefaultArchIfthereIsNotDotNetAssem
         {
             this.mockAssemblyHelper.SetupSequence(ah => ah.GetArchitecture(It.IsAny<string>()))
                 .Returns(Architecture.AnyCPU);
-            Assert.AreEqual(Constants.DefaultPlatform, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "NotDotNetAssebly.appx" }, sourceArchitectures));
+            Assert.AreEqual(DefaultArchitecture, inferHelper.AutoDetectArchitecture(new List<string>() { "AnyCPU1.dll", "NotDotNetAssebly.appx" }, sourceArchitectures, DefaultArchitecture));
             this.mockAssemblyHelper.Verify(ah => ah.GetArchitecture(It.IsAny<string>()), Times.Exactly(1));
         }
 
diff --git a/test/vstest.console.UnitTests/TestPlatformHelpers/TestRequestManagerTests.cs b/test/vstest.console.UnitTests/TestPlatformHelpers/TestRequestManagerTests.cs
index 977a9a2c7c..968d0516da 100644
--- a/test/vstest.console.UnitTests/TestPlatformHelpers/TestRequestManagerTests.cs
+++ b/test/vstest.console.UnitTests/TestPlatformHelpers/TestRequestManagerTests.cs
@@ -262,7 +262,7 @@ public void DiscoverTestsShouldCollectMetrics()
 
             var payload = new DiscoveryRequestPayload()
                               {
-                                  Sources = new List<string>() { "a", "b" },
+                                  Sources = new List<string>() { "a.dll", "b.dll" },
                                   RunSettings = @"<RunSettings>
                                 <RunConfiguration>
                                     <MaxCpuCount>2</MaxCpuCount>
@@ -1063,7 +1063,7 @@ public void RunTestsShouldCollectMetrics()
 
             var payload = new TestRunRequestPayload()
             {
-                Sources = new List<string>() { "a" },
+                Sources = new List<string>() { "a.dll" },
                 RunSettings = @"<RunSettings>
                                 <RunConfiguration>
                                     <MaxCpuCount>2</MaxCpuCount>