diff --git a/src/Microsoft.AspNetCore.Http.Abstractions/HostString.cs b/src/Microsoft.AspNetCore.Http.Abstractions/HostString.cs
index f767255b1f..2641f33540 100644
--- a/src/Microsoft.AspNetCore.Http.Abstractions/HostString.cs
+++ b/src/Microsoft.AspNetCore.Http.Abstractions/HostString.cs
@@ -3,6 +3,7 @@
 
 using System;
 using System.Globalization;
+using Microsoft.AspNetCore.Http.Abstractions;
 
 namespace Microsoft.AspNetCore.Http
 {
@@ -24,6 +25,31 @@ namespace Microsoft.AspNetCore.Http
             _value = value;
         }
 
+        /// <summary>
+        /// Creates a new HostString from its host and port parts.
+        /// </summary>
+        /// <param name="host">The value should be Unicode rather than punycode. IPv6 addresses must use square braces.</param>
+        /// <param name="port">A positive, greater than 0 value representing the port in the host string.</param>
+        public HostString(string host, int port)
+        {
+            if(port <= 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(port), Resources.Exception_PortMustBeGreaterThanZero);
+            }
+
+            int index;
+            if (host.IndexOf('[') == -1
+                && (index = host.IndexOf(':')) >= 0
+                && index < host.Length - 1
+                && host.IndexOf(':', index + 1) >= 0)
+            {
+                // IPv6 without brackets ::1 is the only type of host with 2 or more colons
+                host =  $"[{host}]";
+            }
+
+            _value = host + ":" + port.ToString(CultureInfo.InvariantCulture);
+        }
+
         /// <summary>
         /// Returns the original value from the constructor.
         /// </summary>
@@ -37,6 +63,45 @@ namespace Microsoft.AspNetCore.Http
             get { return !string.IsNullOrEmpty(_value); }
         }
 
+        /// <summary>
+        /// Returns the value of the host part of the value. The port is removed if it was present.
+        /// IPv6 addresses will have brackets added if they are missing.
+        /// </summary>
+        /// <returns></returns>
+        public string Host
+        {
+            get
+            {
+                string host, port;
+
+                GetParts(out host, out port);
+
+                return host;
+            }
+        }
+
+        /// <summary>
+        /// Returns the value of the port part of the host, or <value>null</value> if none is found.
+        /// </summary>
+        /// <returns></returns>
+        public int? Port
+        {
+            get
+            {
+                string host, port;
+                int p;
+
+                GetParts(out host, out port);
+
+                if (string.IsNullOrEmpty(port) || !int.TryParse(port, out p))
+                {
+                    return null;
+                }
+                
+                return p;
+            }
+        }
+
         /// <summary>
         /// Returns the value as normalized by ToUriComponent().
         /// </summary>
@@ -53,35 +118,25 @@ namespace Microsoft.AspNetCore.Http
         /// <returns></returns>
         public string ToUriComponent()
         {
-            int index;
             if (string.IsNullOrEmpty(_value))
             {
                 return string.Empty;
             }
-            else if (_value.IndexOf('[') >= 0)
-            {
-                // IPv6 in brackets [::1], maybe with port
-                return _value;
-            }
-            else if ((index = _value.IndexOf(':')) >= 0
-                && index < _value.Length - 1
-                && _value.IndexOf(':', index + 1) >= 0)
-            {
-                // IPv6 without brackets ::1 is the only type of host with 2 or more colons
-                return $"[{_value}]";
-            }
-            else if (index >= 0)
-            {
-                // Has a port
-                string port = _value.Substring(index);
+
+            string host, port;
+
+            GetParts(out host, out port);
+
+            if (host.IndexOf('[') == -1)
+            { 
                 var mapping = new IdnMapping();
-                return mapping.GetAscii(_value, 0, index) + port;
-            }
-            else
-            {
-                var mapping = new IdnMapping();
-                return mapping.GetAscii(_value);
+                host = mapping.GetAscii(host);
             }
+
+            return string.IsNullOrEmpty(port)
+                ? host
+                : string.Concat(host, ":", port);
+            
         }
 
         /// <summary>
@@ -197,5 +252,49 @@ namespace Microsoft.AspNetCore.Http
         {
             return !left.Equals(right);
         }
+
+        /// <summary>
+        /// Parses the current value. IPv6 addresses will have brackets added if they are missing.
+        /// </summary>
+        private void GetParts(out string host, out string port)
+        {
+            int index;
+            port = null;
+            host = null;
+
+            if (string.IsNullOrEmpty(_value))
+            {
+                return;
+            }
+            else if ((index = _value.IndexOf(']')) >= 0)
+            {
+                // IPv6 in brackets [::1], maybe with port
+                host = _value.Substring(0, index + 1);
+
+                if ((index = _value.IndexOf(':', index + 1)) >= 0)
+                {
+                    port = _value.Substring(index + 1);
+                }
+            }
+            else if ((index = _value.IndexOf(':')) >= 0
+                && index < _value.Length - 1
+                && _value.IndexOf(':', index + 1) >= 0)
+            {
+                // IPv6 without brackets ::1 is the only type of host with 2 or more colons
+                host = $"[{_value}]";
+                port = null;
+            }
+            else if (index >= 0)
+            {
+                // Has a port
+                host = _value.Substring(0, index);
+                port = _value.Substring(index + 1);
+            }
+            else
+            {
+                host = _value;
+                port = null;
+            }
+        }
     }
 }
diff --git a/src/Microsoft.AspNetCore.Http.Abstractions/Properties/Resources.Designer.cs b/src/Microsoft.AspNetCore.Http.Abstractions/Properties/Resources.Designer.cs
index 438644852a..40e4255667 100644
--- a/src/Microsoft.AspNetCore.Http.Abstractions/Properties/Resources.Designer.cs
+++ b/src/Microsoft.AspNetCore.Http.Abstractions/Properties/Resources.Designer.cs
@@ -138,6 +138,22 @@ namespace Microsoft.AspNetCore.Http.Abstractions
             return string.Format(CultureInfo.CurrentCulture, GetString("Exception_InvokeDoesNotSupportRefOrOutParams"), p0);
         }
 
+        /// <summary>
+        /// The value must be greater than zero.
+        /// </summary>
+        internal static string Exception_PortMustBeGreaterThanZero
+        {
+            get { return GetString("Exception_PortMustBeGreaterThanZero"); }
+        }
+
+        /// <summary>
+        /// The value must be greater than zero.
+        /// </summary>
+        internal static string FormatException_PortMustBeGreaterThanZero()
+        {
+            return GetString("Exception_PortMustBeGreaterThanZero");
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);
diff --git a/src/Microsoft.AspNetCore.Http.Abstractions/Resources.resx b/src/Microsoft.AspNetCore.Http.Abstractions/Resources.resx
index 414bad847d..19ce173d19 100644
--- a/src/Microsoft.AspNetCore.Http.Abstractions/Resources.resx
+++ b/src/Microsoft.AspNetCore.Http.Abstractions/Resources.resx
@@ -141,4 +141,7 @@
   <data name="Exception_InvokeDoesNotSupportRefOrOutParams" xml:space="preserve">
     <value>The '{0}' method must not have ref or out parameters.</value>
   </data>
+  <data name="Exception_PortMustBeGreaterThanZero" xml:space="preserve">
+    <value>The value must be greater than zero.</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/test/Microsoft.AspNetCore.Http.Abstractions.Tests/HostStringTest.cs b/test/Microsoft.AspNetCore.Http.Abstractions.Tests/HostStringTest.cs
new file mode 100644
index 0000000000..6e5a684e0b
--- /dev/null
+++ b/test/Microsoft.AspNetCore.Http.Abstractions.Tests/HostStringTest.cs
@@ -0,0 +1,96 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Testing;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Http
+{
+    public class HostStringTests
+    {
+        [Theory]
+        [InlineData(0)]
+        [InlineData(-1)]
+        public void CtorThrows_IfPortIsNotGreaterThanZero(int port)
+        {
+            // Act and Assert
+            ExceptionAssert.ThrowsArgumentOutOfRange(() => new HostString("localhost", port), "port", "The value must be greater than zero.");
+        }
+
+        [Theory]
+        [InlineData("localhost", "localhost")]
+        [InlineData("1.2.3.4", "1.2.3.4")]
+        [InlineData("[2001:db8:a0b:12f0::1]", "[2001:db8:a0b:12f0::1]")]
+        [InlineData("本地主機", "本地主機")]
+        [InlineData("localhost:5000", "localhost")]
+        [InlineData("1.2.3.4:5000", "1.2.3.4")]
+        [InlineData("[2001:db8:a0b:12f0::1]:5000", "[2001:db8:a0b:12f0::1]")]
+        [InlineData("本地主機:5000", "本地主機")]
+        public void Domain_ExtractsHostFromValue(string sourceValue, string expectedDomain)
+        {
+            // Arrange
+            var hostString = new HostString(sourceValue);
+
+            // Act
+            var result = hostString.Host;
+
+            // Assert
+            Assert.Equal(expectedDomain, result);
+        }
+
+        [Theory]
+        [InlineData("localhost", null)]
+        [InlineData("1.2.3.4", null)]
+        [InlineData("[2001:db8:a0b:12f0::1]", null)]
+        [InlineData("本地主機", null)]
+        [InlineData("localhost:5000", 5000)]
+        [InlineData("1.2.3.4:5000", 5000)]
+        [InlineData("[2001:db8:a0b:12f0::1]:5000", 5000)]
+        [InlineData("本地主機:5000", 5000)]
+        public void Port_ExtractsPortFromValue(string sourceValue, int? expectedPort)
+        {
+            // Arrange
+            var hostString = new HostString(sourceValue);
+
+            // Act
+            var result = hostString.Port;
+
+            // Assert
+            Assert.Equal(expectedPort, result);
+        }
+
+        [Theory]
+        [InlineData("localhost:BLAH")]
+        public void Port_ExtractsInvalidPortFromValue(string sourceValue)
+        {
+            // Arrange
+            var hostString = new HostString(sourceValue);
+
+            // Act
+            var result = hostString.Port;
+
+            // Assert
+            Assert.Equal(null, result);
+        }
+
+        [Theory]
+        [InlineData("localhost", 5000, "localhost", 5000)]
+        [InlineData("1.2.3.4", 5000, "1.2.3.4", 5000)]
+        [InlineData("[2001:db8:a0b:12f0::1]", 5000, "[2001:db8:a0b:12f0::1]", 5000)]
+        [InlineData("2001:db8:a0b:12f0::1", 5000, "[2001:db8:a0b:12f0::1]", 5000)]
+        [InlineData("本地主機", 5000, "本地主機", 5000)]
+        public void Ctor_CreatesFromHostAndPort(string sourceHost, int sourcePort, string expectedHost, int expectedPort)
+        {
+            // Arrange
+            var hostString = new HostString(sourceHost, sourcePort);
+
+            // Act
+            var host = hostString.Host;
+            var port = hostString.Port;
+
+            // Assert
+            Assert.Equal(expectedHost, host);
+            Assert.Equal(expectedPort, port);
+        }
+    }
+}