diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/Host.cs b/src/libraries/Microsoft.Extensions.Hosting/src/Host.cs
index f1d095ab0c7e23..69e59b9d5615e8 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/src/Host.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/src/Host.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Collections.Generic;
 using System.IO;
 using System.Reflection;
 using System.Runtime.InteropServices;
@@ -57,9 +58,12 @@ public static IHostBuilder CreateDefaultBuilder(string[] args)
         {
             var builder = new HostBuilder();
 
-            builder.UseContentRoot(Directory.GetCurrentDirectory());
             builder.ConfigureHostConfiguration(config =>
             {
+                config.AddInMemoryCollection(new[]
+                {
+                    new KeyValuePair<string, string> (HostDefaults.ContentRootKey, Directory.GetCurrentDirectory())
+                });
                 config.AddEnvironmentVariables(prefix: "DOTNET_");
                 if (args != null)
                 {
diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.cs b/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.cs
index a36a69858e4c34..98b3525df871f0 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.cs
@@ -147,11 +147,26 @@ private void BuildHostConfiguration()
 
         private void CreateHostingEnvironment()
         {
+            // Explicit settings override config.
+            string environmentName = _hostConfiguration[HostDefaults.EnvironmentKey] ?? Environments.Production;
+            if (Properties.TryGetValue(HostDefaults.EnvironmentKey, out object envObj)
+                && (envObj is string env))
+            {
+                environmentName = env;
+            }
+
+            string contentRoot = _hostConfiguration[HostDefaults.ContentRootKey];
+            if (Properties.TryGetValue(HostDefaults.ContentRootKey, out object contentObj)
+                && (contentObj is string content))
+            {
+                contentRoot = content;
+            }
+
             _hostingEnvironment = new HostingEnvironment()
             {
                 ApplicationName = _hostConfiguration[HostDefaults.ApplicationKey],
-                EnvironmentName = _hostConfiguration[HostDefaults.EnvironmentKey] ?? Environments.Production,
-                ContentRootPath = ResolveContentRootPath(_hostConfiguration[HostDefaults.ContentRootKey], AppContext.BaseDirectory),
+                EnvironmentName = environmentName,
+                ContentRootPath = ResolveContentRootPath(contentRoot, AppContext.BaseDirectory),
             };
 
             if (string.IsNullOrEmpty(_hostingEnvironment.ApplicationName))
diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs b/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs
index ca7e84abff8a07..19a1d9cbbbae02 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
-using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Configuration;
@@ -22,14 +21,8 @@ public static class HostingHostBuilderExtensions
         /// <returns>The <see cref="IHostBuilder"/>.</returns>
         public static IHostBuilder UseEnvironment(this IHostBuilder hostBuilder, string environment)
         {
-            return hostBuilder.ConfigureHostConfiguration(configBuilder =>
-            {
-                configBuilder.AddInMemoryCollection(new[]
-                {
-                    new KeyValuePair<string, string>(HostDefaults.EnvironmentKey,
-                        environment  ?? throw new ArgumentNullException(nameof(environment)))
-                });
-            });
+            hostBuilder.Properties[HostDefaults.EnvironmentKey] = environment;
+            return hostBuilder;
         }
 
         /// <summary>
@@ -40,14 +33,8 @@ public static IHostBuilder UseEnvironment(this IHostBuilder hostBuilder, string
         /// <returns>The <see cref="IHostBuilder"/>.</returns>
         public static IHostBuilder UseContentRoot(this IHostBuilder hostBuilder, string contentRoot)
         {
-            return hostBuilder.ConfigureHostConfiguration(configBuilder =>
-            {
-                configBuilder.AddInMemoryCollection(new[]
-                {
-                    new KeyValuePair<string, string>(HostDefaults.ContentRootKey,
-                        contentRoot  ?? throw new ArgumentNullException(nameof(contentRoot)))
-                });
-            });
+            hostBuilder.Properties[HostDefaults.ContentRootKey] = contentRoot;
+            return hostBuilder;
         }
 
         /// <summary>
diff --git a/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/HostBuilderTests.cs b/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/HostBuilderTests.cs
index 5c1a3b67d1287c..f22810784000bd 100644
--- a/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/HostBuilderTests.cs
+++ b/src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/HostBuilderTests.cs
@@ -202,22 +202,38 @@ public void ConfigBasedSettingsConfigBasedOverride()
         }
 
         [Fact]
-        public void UseEnvironmentIsNotOverriden()
+        public void UseEnvironmentOverridesConfig()
         {
             var vals = new Dictionary<string, string>
             {
-                { "ENV", "Dev" },
+                { HostDefaults.EnvironmentKey, "Dev" },
+            };
+
+            var expected = "MY_TEST_ENVIRONMENT";
+
+            using (var host = new HostBuilder()
+                .ConfigureHostConfiguration(configBuilder => configBuilder.AddInMemoryCollection(vals))
+                .UseEnvironment(expected)
+                .Build())
+            {
+                Assert.Equal(expected, host.Services.GetService<IHostEnvironment>().EnvironmentName);
+            }
+        }
+
+        [Fact]
+        public void UseEnvironmentIsNotOverridenByConfig()
+        {
+            var vals = new Dictionary<string, string>
+            {
+                { HostDefaults.EnvironmentKey, "Dev" },
             };
-            var builder = new ConfigurationBuilder()
-                .AddInMemoryCollection(vals);
-            var config = builder.Build();
 
             var expected = "MY_TEST_ENVIRONMENT";
 
 
             using (var host = new HostBuilder()
-                .ConfigureHostConfiguration(configBuilder => configBuilder.AddConfiguration(config))
                 .UseEnvironment(expected)
+                .ConfigureHostConfiguration(configBuilder => configBuilder.AddInMemoryCollection(vals))
                 .Build())
             {
                 Assert.Equal(expected, host.Services.GetService<IHostEnvironment>().EnvironmentName);
@@ -232,19 +248,44 @@ public void BuildAndDispose()
         }
 
         [Fact]
-        public void UseBasePathConfiguresBasePath()
+        public void UseContentRootConfiguresContentRoot()
+        {
+            using (var host = new HostBuilder()
+                .UseContentRoot("/")
+                .Build())
+            {
+                Assert.Equal("/", host.Services.GetService<IHostEnvironment>().ContentRootPath);
+            }
+        }
+
+        [Fact]
+        public void UseContentRootOverridesConfig()
         {
             var vals = new Dictionary<string, string>
             {
-                { "ENV", "Dev" },
+                { HostDefaults.ContentRootKey, "Foo" },
+            };
+
+            using (var host = new HostBuilder()
+                .ConfigureHostConfiguration(configBuilder => configBuilder.AddInMemoryCollection(vals))
+                .UseContentRoot("/")
+                .Build())
+            {
+                Assert.Equal("/", host.Services.GetService<IHostEnvironment>().ContentRootPath);
+            }
+        }
+
+        [Fact]
+        public void UseContentRootNotOverridenByConfig()
+        {
+            var vals = new Dictionary<string, string>
+            {
+                { HostDefaults.ContentRootKey, "Foo" },
             };
-            var builder = new ConfigurationBuilder()
-                .AddInMemoryCollection(vals);
-            var config = builder.Build();
 
             using (var host = new HostBuilder()
-                .ConfigureHostConfiguration(configBuilder => configBuilder.AddConfiguration(config))
                 .UseContentRoot("/")
+                .ConfigureHostConfiguration(configBuilder => configBuilder.AddInMemoryCollection(vals))
                 .Build())
             {
                 Assert.Equal("/", host.Services.GetService<IHostEnvironment>().ContentRootPath);