diff --git a/global.json b/global.json
index 3f0f8d1b3a14..e1ed7103bbe3 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "2.2.100-preview1-009263"
+    "version": "2.2.100-preview3-009413"
   },
   "msbuild-sdks": {
     "RoslynTools.RepoToolset": "1.0.0-beta2-62912-01"
diff --git a/src/Tasks/Common/MessageBase.cs b/src/Tasks/Common/MessageBase.cs
index 4400899be603..d68a44fdf6ad 100644
--- a/src/Tasks/Common/MessageBase.cs
+++ b/src/Tasks/Common/MessageBase.cs
@@ -12,10 +12,14 @@ namespace Microsoft.NET.Build.Tasks
     /// </summary>
     public abstract class MessageBase : TaskBase
     {
+        /// <summary>
+        /// Formatted text for the message
+        /// </summary>
+        public string FormattedText { get; set; }
+
         /// <summary>
         /// The name of the resource in Strings.resx that contains the desired error message.
         /// </summary>
-        [Required]
         public string ResourceName { get; set; }
 
         /// <summary>
@@ -31,17 +35,34 @@ internal MessageBase()
 
         protected override void ExecuteCore()
         {
-            if (FormatArguments == null || FormatArguments.Length == 0)
+            string message = null;
+            if (string.IsNullOrEmpty(FormattedText) && string.IsNullOrEmpty(ResourceName))
+            {
+                throw new ArgumentException($"Either {nameof(FormattedText)} or {nameof(ResourceName)} must be specified.");
+            }
+            else if (!string.IsNullOrEmpty(FormattedText) && !string.IsNullOrEmpty(ResourceName))
             {
-                // We use a single-item array with one empty string in this case so that
-                // it is possible to interpret FormatArguments="$(EmptyVariable)" as a request
-                // to pass an empty string on to string.Format. Note if there are not placeholders
-                // in the string, then the empty string arg will be ignored.
-                FormatArguments = EmptyArguments;
+                throw new ArgumentException($"Only one of {nameof(FormattedText)} and {nameof(ResourceName)} can be specified.");
             }
+            else if (!string.IsNullOrEmpty(ResourceName))
+            {
+                if (FormatArguments == null || FormatArguments.Length == 0)
+                {
+                    // We use a single-item array with one empty string in this case so that
+                    // it is possible to interpret FormatArguments="$(EmptyVariable)" as a request
+                    // to pass an empty string on to string.Format. Note if there are not placeholders
+                    // in the string, then the empty string arg will be ignored.
+                    FormatArguments = EmptyArguments;
+                }
 
-            string format = Strings.ResourceManager.GetString(ResourceName, Strings.Culture);
-            string message = string.Format(CultureInfo.CurrentCulture, format, FormatArguments);
+                string format = Strings.ResourceManager.GetString(ResourceName, Strings.Culture);
+                message = string.Format(CultureInfo.CurrentCulture, format, FormatArguments);
+            }
+            else
+            {
+                message = FormattedText;
+            }
+            
 
             LogMessage(message);
         }
diff --git a/src/Tasks/Common/MetadataKeys.cs b/src/Tasks/Common/MetadataKeys.cs
index 03f63bcde64d..32b05ceb492e 100644
--- a/src/Tasks/Common/MetadataKeys.cs
+++ b/src/Tasks/Common/MetadataKeys.cs
@@ -16,6 +16,7 @@ internal static class MetadataKeys
         public const string PackageVersion = "PackageVersion";
         public const string IsImplicitlyDefined = "IsImplicitlyDefined";
         public const string IsTopLevelDependency = "IsTopLevelDependency";
+        public const string AllowExplicitVersion = "AllowExplicitVersion";
 
         // Target Metadata
         public const string RuntimeIdentifier = "RuntimeIdentifier";
@@ -81,8 +82,5 @@ internal static class MetadataKeys
         // Resource assemblies
         public const string Culture = "Culture";
         public const string DestinationSubDirectory = "DestinationSubDirectory";
-
-        // Expected platform packages
-        public const string ExpectedVersion = "ExpectedVersion";
     }
 }
diff --git a/src/Tasks/Common/Resources/Strings.resx b/src/Tasks/Common/Resources/Strings.resx
index 5c224b778060..780be934c921 100644
--- a/src/Tasks/Common/Resources/Strings.resx
+++ b/src/Tasks/Common/Resources/Strings.resx
@@ -401,4 +401,7 @@ The following are names of parameters or literal values and should not be transl
     <value>NETSDK1070: The application configuration file must have root configuration element.</value>
     <comment>{StrBegin="NETSDK1070: "}</comment>
   </data>
-</root>
+  <data name="PackageReferenceVersionNotRecommended" xml:space="preserve">
+    <value>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</value>
+  </data>
+</root>
\ No newline at end of file
diff --git a/src/Tasks/Common/Resources/xlf/Strings.cs.xlf b/src/Tasks/Common/Resources/xlf/Strings.cs.xlf
index caa3c1892517..9fcbb4b03aab 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.cs.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.cs.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Chybí metadata {0} o {1} položky {2}.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Nerozpoznaný token preprocesoru {0} v {1}.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.de.xlf b/src/Tasks/Common/Resources/xlf/Strings.de.xlf
index 27cf73b474d7..9f1d2c98bef7 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.de.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.de.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Die Metadaten "{0}" für das Element "{2}" vom Typ "{1}" sind nicht vorhanden.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Unbekanntes Präprozessortoken "{0}" in "{1}".</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.es.xlf b/src/Tasks/Common/Resources/xlf/Strings.es.xlf
index 93f1f3acafc4..bbf74f031892 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.es.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.es.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Faltan los metadatos de "{0}" en el elemento de "{1}" "{2}".</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Token de preprocesador no reconocido "{0}" en "{1}".</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.fr.xlf b/src/Tasks/Common/Resources/xlf/Strings.fr.xlf
index a209ffc3c170..3de69b9fb9ef 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.fr.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.fr.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Métadonnées '{0}' manquantes sur l'élément '{1}' '{2}'.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Jeton de préprocesseur '{0}' non reconnu dans '{1}'.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.it.xlf b/src/Tasks/Common/Resources/xlf/Strings.it.xlf
index c5326b87bd1f..756318f95e89 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.it.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.it.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: mancano i metadati di '{0}' sull'elemento '{2}' di '{1}'.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: token di preprocessore '{0}' non riconosciuto in '{1}'.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.ja.xlf b/src/Tasks/Common/Resources/xlf/Strings.ja.xlf
index 803f87f04baf..bcd063d955e2 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.ja.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.ja.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: '{1}' 項目 '{2}' の '{0}' メタデータがありません。</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: 認識されないプリプロセッサ トークン '{0}' が '{1}' に存在します。</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.ko.xlf b/src/Tasks/Common/Resources/xlf/Strings.ko.xlf
index 1a077a4df692..4bd049d808d1 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.ko.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.ko.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: '{1}' 항목 '{2}'에 '{0}' 메타데이터가 없습니다.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: '{1}'에서 전처리기 토큰 '{0}'을(를) 인식할 수 없습니다.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.pl.xlf b/src/Tasks/Common/Resources/xlf/Strings.pl.xlf
index c62da27f1892..fe44886093f5 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.pl.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.pl.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Brak metadanych „{0}” w elemencie „{1}” „{2}”.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Nierozpoznany token preprocesora „{0}” w elemencie „{1}”.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.pt-BR.xlf b/src/Tasks/Common/Resources/xlf/Strings.pt-BR.xlf
index 8e4fbdc4ce16..81317289abc0 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.pt-BR.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.pt-BR.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: Metadados '{0}' ausentes no item '{1}' '{2}'.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: Token de pré-processador não reconhecido '{0}' em '{1}'.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.ru.xlf b/src/Tasks/Common/Resources/xlf/Strings.ru.xlf
index 4527cffc23b6..bf871d2a21df 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.ru.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.ru.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: отсутствуют метаданные "{0}" для элемента "{2}" в "{1}".</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: не распознан маркер препроцессора "{0}" в "{1}".</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.tr.xlf b/src/Tasks/Common/Resources/xlf/Strings.tr.xlf
index 1d90b1f8dbde..7eb3edd73d1a 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.tr.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.tr.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: '{1}' öğesi '{2}' üzerinde '{0}' meta verileri eksik.</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: '{1}' içinde tanınmayan '{0}' ön işlemci belirteci.</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.zh-Hans.xlf b/src/Tasks/Common/Resources/xlf/Strings.zh-Hans.xlf
index 8a6cdb6454bc..a6359e9eb023 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.zh-Hans.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.zh-Hans.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: 在“{1}”项“{2}”上缺少“{0}”元数据。</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009:“{1}”中无法识别预处理器标记“{0}”。</target>
diff --git a/src/Tasks/Common/Resources/xlf/Strings.zh-Hant.xlf b/src/Tasks/Common/Resources/xlf/Strings.zh-Hant.xlf
index 27b81bd4139f..abf2651cca49 100644
--- a/src/Tasks/Common/Resources/xlf/Strings.zh-Hant.xlf
+++ b/src/Tasks/Common/Resources/xlf/Strings.zh-Hant.xlf
@@ -67,6 +67,11 @@
         <target state="translated">NETSDK1008: '{1}' 項目 '{2}' 上遺漏 '{0}' 中繼資料。</target>
         <note>{StrBegin="NETSDK1008: "}</note>
       </trans-unit>
+      <trans-unit id="PackageReferenceVersionNotRecommended">
+        <source>NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</source>
+        <target state="new">NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs</target>
+        <note />
+      </trans-unit>
       <trans-unit id="UnrecognizedPreprocessorToken">
         <source>NETSDK1009: Unrecognized preprocessor token '{0}' in '{1}'.</source>
         <target state="translated">NETSDK1009: '{1}' 中的前置處理器語彙基元 '{0}' 無法辨識。</target>
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/ApplyImplicitVersions.cs b/src/Tasks/Microsoft.NET.Build.Tasks/ApplyImplicitVersions.cs
new file mode 100644
index 000000000000..04ed9756e504
--- /dev/null
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ApplyImplicitVersions.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using Microsoft.Build.Framework;
+
+namespace Microsoft.NET.Build.Tasks
+{
+    public sealed class ApplyImplicitVersions : TaskBase
+    {
+        public string TargetFrameworkVersion { get; set; }
+
+        public bool TargetLatestRuntimePatch { get; set; }
+
+        public ITaskItem[] PackageReferences { get; set; } = Array.Empty<ITaskItem>();
+
+        public ITaskItem[] ImplicitPackageReferenceVersions { get; set; } = Array.Empty<ITaskItem>();
+
+        [Output]
+        public ITaskItem[] PackageReferencesToUpdate { get; private set; }
+
+        //  This task runs both before restore and build, so if it logged warnings directly they could show up
+        //  twice when building with implicit restore.  So instead we generate the warnings here, and keep them
+        //  in an item where they'll be logged in a target that runs before build, but not before restore.
+        [Output]
+        public string[] SdkBuildWarnings { get; private set; }
+
+        protected override void ExecuteCore()
+        {
+            List<string> buildWarnings = new List<string>();
+
+            var packageReferencesToUpdate = new List<ITaskItem>();
+
+            var implicitVersionTable = GetApplicableImplicitVersionTable();
+
+            foreach (var packageReference in PackageReferences)
+            {
+                ImplicitPackageReferenceVersion implicitVersion;
+                if (implicitVersionTable.TryGetValue(packageReference.ItemSpec, out implicitVersion))
+                {
+                    string versionOnPackageReference = packageReference.GetMetadata(MetadataKeys.Version);
+                    if (string.IsNullOrEmpty(versionOnPackageReference))
+                    {
+                        packageReference.SetMetadata(MetadataKeys.Version, 
+                            TargetLatestRuntimePatch ? implicitVersion.LatestVersion : implicitVersion.DefaultVersion);
+
+                        packageReference.SetMetadata(MetadataKeys.IsImplicitlyDefined, "true");
+
+                        packageReferencesToUpdate.Add(packageReference);
+                    }
+                    else if (!(packageReference.GetBooleanMetadata(MetadataKeys.AllowExplicitVersion) ?? false))
+                    {
+                        // NETSDK1071: A PackageReference to '{0}' specified a Version of `{1}`. Specifying the version of this package is not recommended.  For more information, see https://aka.ms/sdkimplicitrefs
+                        buildWarnings.Add(string.Format(Strings.PackageReferenceVersionNotRecommended, packageReference.ItemSpec, versionOnPackageReference));
+                    }
+                }
+            }
+
+            PackageReferencesToUpdate = packageReferencesToUpdate.ToArray();
+            SdkBuildWarnings = buildWarnings.ToArray();
+        }
+
+        private Dictionary<string, ImplicitPackageReferenceVersion> GetApplicableImplicitVersionTable()
+        {
+            var result = new Dictionary<string, ImplicitPackageReferenceVersion>();
+            foreach (var item in ImplicitPackageReferenceVersions)
+            {
+                var implicitPackageReferenceVersion = new ImplicitPackageReferenceVersion(item);
+
+                if (implicitPackageReferenceVersion.TargetFrameworkVersion == this.TargetFrameworkVersion)
+                {
+                    result.Add(implicitPackageReferenceVersion.Name, implicitPackageReferenceVersion);
+                }
+            }
+
+            return result;
+        }
+
+        private sealed class ImplicitPackageReferenceVersion
+        {
+            private ITaskItem _item;
+
+            public ImplicitPackageReferenceVersion(ITaskItem item)
+            {
+                _item = item;
+            }
+
+            //  The name / Package ID
+            public string Name => _item.ItemSpec;
+
+            //  The target framework version that this item applies to
+            public string TargetFrameworkVersion => _item.GetMetadata("TargetFrameworkVersion");
+
+            public string DefaultVersion => _item.GetMetadata("DefaultVersion");
+
+            public string LatestVersion => _item.GetMetadata("LatestVersion");
+        }
+    }
+}
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/CheckForImplicitPackageReferenceOverrides.cs b/src/Tasks/Microsoft.NET.Build.Tasks/CheckForImplicitPackageReferenceOverrides.cs
index 797469145139..0f41660272aa 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/CheckForImplicitPackageReferenceOverrides.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/CheckForImplicitPackageReferenceOverrides.cs
@@ -9,8 +9,6 @@ namespace Microsoft.NET.Build.Tasks
 {
     public class CheckForImplicitPackageReferenceOverrides : TaskBase
     {
-        const string MetadataKeyForItemsToRemove = "IsImplicitlyDefined";
-
         [Required]
         public ITaskItem [] PackageReferenceItems { get; set; }
 
@@ -20,21 +18,41 @@ public class CheckForImplicitPackageReferenceOverrides : TaskBase
         [Output]
         public ITaskItem[] ItemsToRemove { get; set; }
 
+        [Output]
+        public ITaskItem[] ItemsToAdd { get; set; }
+
         protected override void ExecuteCore()
         {
             var duplicateItems = PackageReferenceItems.GroupBy(i => i.ItemSpec, StringComparer.OrdinalIgnoreCase).Where(g => g.Count() > 1);
-            var duplicateItemsToRemove = duplicateItems.SelectMany(g => g.Where(
-                item => item.GetMetadata(MetadataKeyForItemsToRemove).Equals("true", StringComparison.OrdinalIgnoreCase)));
 
-            ItemsToRemove = duplicateItemsToRemove.ToArray();
-
-            foreach (var itemToRemove in ItemsToRemove)
+            if (duplicateItems.Any())
             {
-                string message = string.Format(CultureInfo.CurrentCulture, Strings.PackageReferenceOverrideWarning,
-                    itemToRemove.ItemSpec,
-                    MoreInformationLink);
-
-                Log.LogWarning(message);
+                List<ITaskItem> itemsToRemove = new List<ITaskItem>();
+                List<ITaskItem> itemsToAdd = new List<ITaskItem>();
+                foreach (var duplicateItemGroup in duplicateItems)
+                {
+                    foreach (var item in duplicateItemGroup)
+                    {
+                        if (item.GetMetadata(MetadataKeys.IsImplicitlyDefined).Equals("true", StringComparison.OrdinalIgnoreCase))
+                        {
+                            itemsToRemove.Add(item);
+  
+                            Log.LogWarning(Strings.PackageReferenceOverrideWarning, item.ItemSpec, MoreInformationLink);
+                        }
+                        else
+                        {
+                            //  For the explicit items, we want to add metadata to them so that the ApplyImplicitVersions task
+                            //  won't generate another error.  The easiest way to do this is to add them both to a list of
+                            //  items to remove, and then a list of items which gets added back.
+                            itemsToRemove.Add(item);
+                            item.SetMetadata(MetadataKeys.AllowExplicitVersion, "true");
+                            itemsToAdd.Add(item);
+                        }
+                    }
+                }
+
+                ItemsToRemove = itemsToRemove.ToArray();
+                ItemsToAdd = itemsToAdd.ToArray();
             }
         }
     }
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/ResolvePackageAssets.cs b/src/Tasks/Microsoft.NET.Build.Tasks/ResolvePackageAssets.cs
index a737753cf7c2..956637da0ed7 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/ResolvePackageAssets.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ResolvePackageAssets.cs
@@ -341,7 +341,7 @@ internal byte[] HashSettings()
                         foreach (var implicitPackage in ExpectedPlatformPackages)
                         {
                             writer.Write(implicitPackage.ItemSpec ?? "");
-                            writer.Write(implicitPackage.GetMetadata(MetadataKeys.ExpectedVersion) ?? "");
+                            writer.Write(implicitPackage.GetMetadata(MetadataKeys.Version) ?? "");
                         }
                     }
                     writer.Write(ProjectAssetsCacheFile);
@@ -849,10 +849,10 @@ bool hasTwoPeriods(string s)
                 if (_task.VerifyMatchingImplicitPackageVersion &&
                     _task.ExpectedPlatformPackages != null)
                 {
-                    foreach (var implicitPackge in _task.ExpectedPlatformPackages)
+                    foreach (var implicitPackage in _task.ExpectedPlatformPackages)
                     {
-                        var packageName = implicitPackge.ItemSpec;
-                        var expectedVersion = implicitPackge.GetMetadata(MetadataKeys.ExpectedVersion);
+                        var packageName = implicitPackage.ItemSpec;
+                        var expectedVersion = implicitPackage.GetMetadata(MetadataKeys.Version);
 
                         if (string.IsNullOrEmpty(packageName) ||
                             string.IsNullOrEmpty(expectedVersion) ||
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets
index 3ca593b1fb99..1fee24a9b003 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.CrossGen.targets
@@ -258,15 +258,22 @@ Restores netcoreapp and publishes it to a temp directory
   
   <Target Name="_RestoreCrossgen"
           DependsOnTargets="PrepforRestoreForComposeStore;
-                           _SetupStageForCrossgen;"
+                           _SetupStageForCrossgen;
+                           ApplyImplicitVersions"
           Condition="$(SkipOptimization) != 'true' ">
+
+    <ItemGroup>
+      <!-- Filter package references to the one for the platform library, in order to find the right version -->
+      <PackageReferenceForCrossGen Include="@(PackageReference)" Condition="'%(Identity)' == '$(MicrosoftNETPlatformLibrary)'" />
+    </ItemGroup>
+
     <MSBuild Projects="$(MSBuildProjectFullPath)"
                  Targets="Restore"
                  Properties="RestoreGraphProjectInput=$(MSBuildProjectFullPath);
                              DisableImplicitFrameworkReferences=true;
                              RestoreOutputPath=$(_CrossProjFileDir);
                              StorePackageName=$(MicrosoftNETPlatformLibrary);
-                             StorePackageVersion=$(RuntimeFrameworkVersion);"/>
+                             StorePackageVersion=%(PackageReferenceForCrossGen.Version);"/>
 
     <ResolvePublishAssemblies ProjectPath="$(MSBuildProjectFullPath)"
                               AssetsFilePath="$(_CrossProjAssetsFile)"
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.props b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.props
index 05b266dda866..8c019f4ded32 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.props
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.props
@@ -19,6 +19,9 @@ Copyright (c) .NET Foundation. All rights reserved.
 
   <PropertyGroup>
     <MSBuildAllProjects>$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
+
+    <!-- Disable web SDK implicit package versions for ASP.NET packages, since the .NET SDK now handles that -->
+    <EnableWebSdkImplicitPackageVersions>false</EnableWebSdkImplicitPackageVersions>
   </PropertyGroup>
 
 
@@ -46,7 +49,7 @@ Copyright (c) .NET Foundation. All rights reserved.
   </ItemGroup>
 
   <ItemGroup Condition=" '$(DisableImplicitFrameworkReferences)' != 'true' and '$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-    <PackageReference Include="Microsoft.NETCore.App" Version="$(RuntimeFrameworkVersion)" IsImplicitlyDefined="true" />
+    <PackageReference Include="Microsoft.NETCore.App" IsImplicitlyDefined="true" />
 
     <!-- For targeting .NET Core 2.0 or higher, don't include a dependency on Microsoft.NETCore.App in the package produced by pack.
          Packing an DotnetCliTool should include the Microsoft.NETCore.App package dependency. -->
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.targets b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.targets
index a89fca2790ef..a0553517df26 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.targets
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.targets
@@ -76,85 +76,82 @@ Copyright (c) .NET Foundation. All rights reserved.
     The TargetLatestRuntimePatch property can be set to true or false to explicitly opt in or out of the logic to roll forward
     to the latest patch, regardless of whether the app is self-contained or framework-dependent.
     
-    The RuntimeFrameworkVersion is where the actual version of the .NET Core runtime to target is stored.  It is the version that is
-    used in the implicit PackageReference to Microsoft.NETCore.App.  The RuntimeFrameworkVersion can also be set explicitly, which
-    will disable all the other logic that automatically selects the version of .NET Core to target.
+    The RuntimeFrameworkVersion is where the actual version of the .NET Core runtime to target can be set.  If set, it will be
+    used in the implicit PackageReference to Microsoft.NETCore.App.  
     
     The framework version that is written to the runtimeconfig.json file is based on the actual resolved package version
     of Microsoft.NETCore.App.  This is to allow floating the verion number (ie the RuntimeFrameworkVersion could be set to
     "2.0-*".
   
   -->
-
-  <!--
-      Possible property names to enable roll-forward:
-      - TargetLatestRuntimePatch
-      - TargetLatestNetCoreRuntimePatch
-      - RollForwardRuntime
-      - RollForwardNetCoreRuntime
-      
-     Possible property names for roll-forward/not roll-forward versions
-      - LatestNetCorePatchVersion / DefaultNetCorePatchVersion
-      
-      TODO: Get feedback on these names and then delete this comment
-  -->
-
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">
-    <!-- These properties will allow the latest patch versions to be set in the CLI (via BundledVersions.props) or overridden by tests -->
-    <LatestPatchVersionForNetCore1_0 Condition="'$(LatestPatchVersionForNetCore1_0)' == ''">1.0.10</LatestPatchVersionForNetCore1_0>
-    <LatestPatchVersionForNetCore1_1 Condition="'$(LatestPatchVersionForNetCore1_1)' == ''">1.1.7</LatestPatchVersionForNetCore1_1>
-    <LatestPatchVersionForNetCore2_0 Condition="'$(LatestPatchVersionForNetCore2_0)' == ''">2.0.6</LatestPatchVersionForNetCore2_0>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(DefaultNetCorePatchVersion)' == ''">
-    <DefaultNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '1.0'">1.0.5</DefaultNetCorePatchVersion>
-    <DefaultNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '1.1'">1.1.2</DefaultNetCorePatchVersion>
-
-    <!-- If targeting the same pre-release that is bundled with the .NET Core SDK, use the bundled package version
-         provided by Microsoft.NETCoreSdk.BundledVersions.props -->
-    <DefaultNetCorePatchVersion Condition="'$(DefaultNetCorePatchVersion)' == '' And '$(_TargetFrameworkVersionWithoutV)' == '$(BundledNETCoreAppTargetFrameworkVersion)' And '$(UseBundledNETCoreAppPackageVersionAsDefaultNetCorePatchVersion)' == 'true'">$(BundledNETCoreAppPackageVersion)</DefaultNetCorePatchVersion>
-    <!-- If not covered by the previous cases use the target framework version for the default patch version -->
-    <DefaultNetCorePatchVersion Condition="'$(DefaultNetCorePatchVersion)' == ''">$(_TargetFrameworkVersionWithoutV)</DefaultNetCorePatchVersion>
-  </PropertyGroup>
-
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(LatestNetCorePatchVersion)' == ''">
-    <LatestNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '1.0'">$(LatestPatchVersionForNetCore1_0)</LatestNetCorePatchVersion>
-    <LatestNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '1.1'">$(LatestPatchVersionForNetCore1_1)</LatestNetCorePatchVersion>
-    <LatestNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '2.0'">$(LatestPatchVersionForNetCore2_0)</LatestNetCorePatchVersion>
-    <LatestNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '2.1'">$(LatestPatchVersionForNetCore2_1)</LatestNetCorePatchVersion>
-
-    <!-- If targeting the same pre-release that is bundled with the .NET Core SDK, use the bundled package version
-         provided by Microsoft.NETCoreSdk.BundledVersions.props -->
-    <LatestNetCorePatchVersion Condition="'$(_TargetFrameworkVersionWithoutV)' == '$(BundledNETCoreAppTargetFrameworkVersion)'">$(BundledNETCoreAppPackageVersion)</LatestNetCorePatchVersion>
-    <!-- If not covered by the previous cases use the target framework version for the latest patch version -->
-    <LatestNetCorePatchVersion Condition="'$(LatestNetCorePatchVersion)' == ''">$(_TargetFrameworkVersionWithoutV)</LatestNetCorePatchVersion>
-  </PropertyGroup>
   
   <PropertyGroup Condition="'$(TargetLatestRuntimePatch)' == ''">
     <TargetLatestRuntimePatch Condition="'$(SelfContained)' == 'true' ">true</TargetLatestRuntimePatch>
     <TargetLatestRuntimePatch Condition="'$(SelfContained)' != 'true' ">false</TargetLatestRuntimePatch>
   </PropertyGroup>
 
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(RuntimeFrameworkVersion)' == ''">
-    <RuntimeFrameworkVersion Condition="'$(TargetLatestRuntimePatch)' == 'true' ">$(LatestNetCorePatchVersion)</RuntimeFrameworkVersion>
-    <RuntimeFrameworkVersion Condition="'$(TargetLatestRuntimePatch)' != 'true' ">$(DefaultNetCorePatchVersion)</RuntimeFrameworkVersion>
+  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(DisableImplicitFrameworkReferences)' != 'true'">
+    <VerifyMatchingImplicitPackageVersion Condition="'$(VerifyMatchingImplicitPackageVersion)' == ''">true</VerifyMatchingImplicitPackageVersion>
   </PropertyGroup>
 
-  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(DisableImplicitFrameworkReferences)' != 'true'">
-    <!-- This property is different than MicrosoftNETPlatformLibrary.  MicrosoftNETPlatformLibrary is
-         used to trim the dependencies published with a framework-dependent app, and is overridden
-         by ASP.NET packages.
-         
-         ExpectedPlatformPackages is the list of packages that are actually implicitly
-         referenced by the SDK, and is passed into the ResolvePackageAssets task
-         to verify that the restored versions of the packages matches the expected versions
-         -->
-    <ExpectedPlatformPackages Include="Microsoft.NETCore.App" ExpectedVersion="$(RuntimeFrameworkVersion)" />
+  <ItemGroup>
+    <!-- Set implicit metadata on ASP.NET package references -->
+    <PackageReference Update="Microsoft.AspNetCore.App">
+      <PrivateAssets Condition="'%(PackageReference.Version)' == ''">true</PrivateAssets>
+      <Publish Condition="'%(PackageReference.Version)' == ''">true</Publish>
+    </PackageReference>
+  
+    <PackageReference Update="Microsoft.AspNetCore.All">
+      <PrivateAssets Condition="'%(PackageReference.Version)' == ''">true</PrivateAssets>
+      <Publish Condition="'%(PackageReference.Version)' == ''">true</Publish>
+    </PackageReference>
+  
+    <!-- Allow RuntimeFrameworkVersion to be used to explicitly specify the version of Microsoft.NETCore.App -->
+    <PackageReference Update="Microsoft.NETCore.App"
+                      Version="$(RuntimeFrameworkVersion)"
+                      Condition="'$(RuntimeFrameworkVersion)' != ''" 
+                      AllowExplicitVersion="true"/>
+    
+    <!-- If implicit PackageReferences are disabled, then don't warn about explicit versions at all -->
+    <PackageReference Update="@(PackageReference)"
+                      Condition="'$(DisableImplicitFrameworkReferences)' == 'true'"
+                      AllowExplicitVersion="true"/>
   </ItemGroup>
+  
+  <UsingTask TaskName="ApplyImplicitVersions" AssemblyFile="$(MicrosoftNETBuildTasksAssembly)" />
+
+  <Target Name="ApplyImplicitVersions" BeforeTargets="_CheckForInvalidConfigurationAndPlatform;CollectPackageReferences"
+          DependsOnTargets="CheckForImplicitPackageReferenceOverrides">
+    <ApplyImplicitVersions TargetFrameworkVersion="$(_TargetFrameworkVersionWithoutV)"
+                           TargetLatestRuntimePatch="$(TargetLatestRuntimePatch)"
+                           PackageReferences="@(PackageReference)"
+                           ImplicitPackageReferenceVersions="@(ImplicitPackageReferenceVersion)">
+      <Output TaskParameter="PackageReferencesToUpdate" ItemName="PackageReferenceToUpdate" />
+      <Output TaskParameter="SdkBuildWarnings" ItemName="SdkBuildWarning" />
+    </ApplyImplicitVersions>
 
-  <PropertyGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp' And '$(DisableImplicitFrameworkReferences)' != 'true'">
-    <VerifyMatchingImplicitPackageVersion Condition="'$(VerifyMatchingImplicitPackageVersion)' == ''">true</VerifyMatchingImplicitPackageVersion>
-  </PropertyGroup>
+    <ItemGroup>
+      <PackageReference Remove="@(PackageReferenceToUpdate)" />
+      <PackageReference Include="@(PackageReferenceToUpdate)" />
+    </ItemGroup>
+
+    <ItemGroup>
+      <!-- Support using a patch version in the TargetFramework, ie netcoreapp1.1.1
+           Note that this isn't officially supported, but it worked in the past so
+           this should prevent breaking it. -->
+      <PackageReference Condition="'%(PackageReference.Identity)' == 'Microsoft.NETCore.App'">
+        <Version Condition="'%(PackageReference.Version)' == ''">$(_TargetFrameworkVersionWithoutV)</Version>
+      </PackageReference>
+    </ItemGroup>
+  </Target>
+  
+  <!-- This target runs before build but not before restore, to avoid duplicating these warnings
+       if building with an implicit restore. -->
+  <Target Name="WarnForExplicitVersions" BeforeTargets="_CheckForInvalidConfigurationAndPlatform"
+          DependsOnTargets="ApplyImplicitVersions"
+          Condition="'@(SdkBuildWarning)' != ''">
+    <NetSdkWarning FormattedText="%(SdkBuildWarning.Identity)" />
+  </Target>
   
   <!--
     Automatically add Link metadata to items of specific types if they are outside of the project folder and don't already have the Link metadata set.
@@ -215,12 +212,14 @@ Copyright (c) .NET Foundation. All rights reserved.
         PackageReferenceItems="@(PackageReference)"
         MoreInformationLink="$(ImplicitPackageReferenceInformationLink)">
       <Output TaskParameter="ItemsToRemove" ItemName="_PackageReferenceToRemove" />
+      <Output TaskParameter="ItemsToAdd" ItemName="_PackageReferenceToAdd" />
     </CheckForImplicitPackageReferenceOverrides>
 
     <ItemGroup>
-      <!-- Note that the condition here is important, otherwise the Remove will operate based just on item identity and remove all items
-           that had duplicates, instead of leaving the ones without IsImplicitlyDefined set to true. -->
-      <PackageReference Remove="@(_PackageReferenceToRemove)" Condition="'%(PackageReference.IsImplicitlyDefined)' == 'true' "/>
+      <!-- Remove and add the PackageReference items according to the output from the task -->
+      <PackageReference Remove="@(_PackageReferenceToRemove)" />
+
+      <PackageReference Include="@(_PackageReferenceToAdd)" />
     </ItemGroup>
     
     <!-- If any implicit package references were overridden, then don't check that RuntimeFrameworkVersion matches the package version -->
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.PackageDependencyResolution.targets b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.PackageDependencyResolution.targets
index 0c5c9ccb43c3..bbb14fcee06c 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.PackageDependencyResolution.targets
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.PackageDependencyResolution.targets
@@ -197,6 +197,12 @@ Copyright (c) .NET Foundation. All rights reserved.
 
     <ItemGroup>
       <_PackAsToolShimRuntimeIdentifiers Include="$(PackAsToolShimRuntimeIdentifiers)"/>
+
+      <!-- Pass these packages into the ResolvePackageAssets task to verify that the restored versions of the packages
+           match the expected version -->
+      <ExpectedPlatformPackages Include="@(PackageReference)" Condition="'%(Identity)' == 'Microsoft.NETCore.App'" />
+      <ExpectedPlatformPackages Include="@(PackageReference)" Condition="'%(Identity)' == 'Microsoft.AspNetCore.App'" />
+      <ExpectedPlatformPackages Include="@(PackageReference)" Condition="'%(Identity)' == 'Microsoft.AspNetCore.All'" />
     </ItemGroup>
 
     <ResolvePackageAssets 
diff --git a/src/Tests/Microsoft.NET.Build.Tests/GivenThereAreDefaultItems.cs b/src/Tests/Microsoft.NET.Build.Tests/GivenThereAreDefaultItems.cs
index ecf5281d0ce3..3b0ab835d14d 100644
--- a/src/Tests/Microsoft.NET.Build.Tests/GivenThereAreDefaultItems.cs
+++ b/src/Tests/Microsoft.NET.Build.Tests/GivenThereAreDefaultItems.cs
@@ -640,7 +640,10 @@ public void Implicit_NetCoreApp_reference_can_be_overridden(bool disableImplicit
             buildCommand
                 .Execute()
                 .Should()
-                .Pass();
+                .Pass()
+                .And
+                .NotHaveStdOutContaining("NETSDK1071");
+                ;
 
             LockFile lockFile = LockFileUtilities.GetLockFile(Path.Combine(buildCommand.ProjectRootPath, "obj", "project.assets.json"), NullLogger.Instance);
 
diff --git a/src/Tests/Microsoft.NET.Build.Tests/ImplicitAspNetVersions.cs b/src/Tests/Microsoft.NET.Build.Tests/ImplicitAspNetVersions.cs
new file mode 100644
index 000000000000..006ec53ee392
--- /dev/null
+++ b/src/Tests/Microsoft.NET.Build.Tests/ImplicitAspNetVersions.cs
@@ -0,0 +1,208 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using FluentAssertions;
+using Microsoft.NET.TestFramework;
+using Microsoft.NET.TestFramework.Assertions;
+using Microsoft.NET.TestFramework.Commands;
+using Microsoft.NET.TestFramework.ProjectConstruction;
+using NuGet.Common;
+using NuGet.Frameworks;
+using NuGet.ProjectModel;
+using NuGet.Versioning;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Microsoft.NET.Build.Tests
+{
+    public class ImplicitAspNetVersions : SdkTest
+    {
+        public ImplicitAspNetVersions(ITestOutputHelper log) : base(log)
+        {
+        }
+
+        [Theory]
+        [InlineData("Microsoft.AspNetCore.App")]
+        [InlineData("Microsoft.AspNetCore.All")]
+        public void AspNetCoreVersionIsSetImplicitly(string aspnetPackageName)
+        {
+            var testProject = new TestProject()
+            {
+                Name = "AspNetImplicitVersion",
+                TargetFrameworks = "netcoreapp2.1",
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            //  Add versionless PackageReference
+            testProject.PackageReferences.Add(new TestPackageReference(aspnetPackageName, null));
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject, identifier: aspnetPackageName)
+                .Restore(Log, testProject.Name);
+
+            var buildCommand = new BuildCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass();
+
+            var aspnetVersion = GetLibraryVersion(testProject, buildCommand, aspnetPackageName);
+
+            //  Version of AspNetCore packages is 2.1.1 because 2.1.0 packages had exact version constraints, which was broken
+            aspnetVersion.ToString().Should().Be("2.1.1");
+        }
+
+        [Theory]
+        [InlineData("Microsoft.AspNetCore.App")]
+        [InlineData("Microsoft.AspNetCore.All")]
+        public void AspNetCoreVersionRollsForward(string aspnetPackageName)
+        {
+            var testProject = new TestProject()
+            {
+                Name = "AspNetImplicitVersion",
+                TargetFrameworks = "netcoreapp2.1",
+                IsSdkProject = true,
+                IsExe = true,
+                
+            };
+
+            testProject.RuntimeIdentifier = EnvironmentInfo.GetCompatibleRid(testProject.TargetFrameworks);
+
+            //  Add versionless PackageReference
+            testProject.PackageReferences.Add(new TestPackageReference(aspnetPackageName, null));
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject, identifier: aspnetPackageName)
+                .Restore(Log, testProject.Name);
+
+            var buildCommand = new BuildCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass();
+
+            var aspnetVersion = GetLibraryVersion(testProject, buildCommand, aspnetPackageName);
+
+            //  Self-contained app (because RID is specified) should roll forward to later patch
+            aspnetVersion.CompareTo(new SemanticVersion(2, 1, 1)).Should().BeGreaterThan(0);
+        }
+
+        [Theory]
+        [InlineData("Microsoft.AspNetCore.App")]
+        [InlineData("Microsoft.AspNetCore.All")]
+        public void ExplicitVersionsOfAspNetCoreWarn(string aspnetPackageName)
+        {
+            var testProject = new TestProject()
+            {
+                Name = "AspNetExplicitVersion",
+                TargetFrameworks = "netcoreapp2.1",
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            string explicitVersion = "2.1.0";
+
+            testProject.PackageReferences.Add(new TestPackageReference(aspnetPackageName, explicitVersion));
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject, identifier: aspnetPackageName)
+                .Restore(Log, testProject.Name);
+
+            var buildCommand = new BuildCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .HaveStdOutContaining("NETSDK1071");
+
+            var aspnetVersion = GetLibraryVersion(testProject, buildCommand, aspnetPackageName);
+
+            aspnetVersion.ToString().Should().Be(explicitVersion);
+        }
+
+        [Theory]
+        [InlineData("netcoreapp2.0", "Microsoft.AspNetCore.All", "2.0.9")]
+        [InlineData("netcoreapp1.1", "Microsoft.AspNetCore", "1.1.7")]
+        public void ExplicitVersionsDontWarnForOlderVersions(string targetFramework, string packageName, string packageVersion)
+        {
+            var testProject = new TestProject()
+            {
+                Name = "AspNetPreviousVersion",
+                TargetFrameworks = targetFramework,
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            testProject.PackageReferences.Add(new TestPackageReference(packageName, packageVersion));
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject, identifier: targetFramework)
+                .Restore(Log, testProject.Name);
+
+            var buildCommand = new BuildCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .NotHaveStdOutContaining("warning");
+
+            var aspnetVersion = GetLibraryVersion(testProject, buildCommand, packageName);
+
+            aspnetVersion.ToString().Should().Be(packageVersion);
+        }
+
+        [Fact]
+        public void MultipleWarningsAreGeneratedForMultipleExplicitReferences()
+        {
+            var testProject = new TestProject()
+            {
+                Name = "MultipleExplicitReferences",
+                TargetFrameworks = "netcoreapp2.1",
+                IsSdkProject = true,
+                IsExe = true
+            };
+
+            testProject.PackageReferences.Add(new TestPackageReference("Microsoft.NETCore.App", "2.1.0"));
+            testProject.PackageReferences.Add(new TestPackageReference("Microsoft.AspNetCore.App", "2.1.0"));
+
+            var testAsset = _testAssetsManager.CreateTestProject(testProject);
+
+            var restoreCommand = new RestoreCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+            restoreCommand
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .NotHaveStdOutContaining("NETSDK1071");
+                
+
+            var buildCommand = new BuildCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name));
+
+            buildCommand
+                .Execute()
+                .Should()
+                .Pass()
+                .And
+                .HaveStdOutContaining("NETSDK1071")
+                .And
+                .HaveStdOutContaining("NETSDK1023");
+        }
+
+        static NuGetVersion GetLibraryVersion(TestProject testProject, BuildCommand buildCommand, string libraryName)
+        {
+            LockFile lockFile = LockFileUtilities.GetLockFile(
+                Path.Combine(buildCommand.GetBaseIntermediateDirectory().FullName, "project.assets.json"),
+                NullLogger.Instance);
+
+            var target = lockFile.GetTarget(NuGetFramework.Parse(testProject.TargetFrameworks), testProject.RuntimeIdentifier);
+            var lockFileLibrary = target.Libraries.Single(l => l.Name == libraryName);
+
+            return lockFileLibrary.Version;
+        }
+    }
+}
diff --git a/src/Tests/Microsoft.NET.Publish.Tests/GivenThatAPublishedDepsJsonShouldContainVersionInformation.cs b/src/Tests/Microsoft.NET.Publish.Tests/GivenThatAPublishedDepsJsonShouldContainVersionInformation.cs
index 5957071f09d5..ca568ae07db0 100644
--- a/src/Tests/Microsoft.NET.Publish.Tests/GivenThatAPublishedDepsJsonShouldContainVersionInformation.cs
+++ b/src/Tests/Microsoft.NET.Publish.Tests/GivenThatAPublishedDepsJsonShouldContainVersionInformation.cs
@@ -15,6 +15,9 @@
 using Microsoft.NET.TestFramework.Commands;
 using Microsoft.NET.TestFramework.ProjectConstruction;
 using Newtonsoft.Json.Linq;
+using NuGet.Common;
+using NuGet.Frameworks;
+using NuGet.ProjectModel;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -254,15 +257,14 @@ string GetRollForwardNetCoreAppVersion()
 
             var testAsset = _testAssetsManager.CreateTestProject(testProject)
                 .Restore(Log, testProject.Name);
-            var getValuesCommand = new GetValuesCommand(Log, Path.Combine(testAsset.TestRoot, testProject.Name),
-                        testProject.TargetFrameworks, "RuntimeFrameworkVersion")
-            {
-                ShouldCompile = false
-            };
 
-            getValuesCommand.Execute().Should().Pass();
+            LockFile lockFile = LockFileUtilities.GetLockFile(Path.Combine(testAsset.TestRoot, testProject.Name,
+                                            "obj", "project.assets.json"), NullLogger.Instance);
+
+            var target = lockFile.GetTarget(NuGetFramework.Parse(testProject.TargetFrameworks), null);
+            var netCoreAppLibrary = target.Libraries.Single(l => l.Name == "Microsoft.NETCore.App");
 
-            return getValuesCommand.GetValues().Single();
+            return netCoreAppLibrary.Version.ToString();
         }
     }
 }
diff --git a/src/Tests/Microsoft.NET.TestFramework/ProjectConstruction/TestProject.cs b/src/Tests/Microsoft.NET.TestFramework/ProjectConstruction/TestProject.cs
index 6e91bd2f7d77..0ffb53c2e53d 100644
--- a/src/Tests/Microsoft.NET.TestFramework/ProjectConstruction/TestProject.cs
+++ b/src/Tests/Microsoft.NET.TestFramework/ProjectConstruction/TestProject.cs
@@ -145,9 +145,13 @@ internal void Create(TestAsset targetTestAsset, string testProjectsSourceFolder)
 
             foreach (TestPackageReference packageReference in PackageReferences)
             {
-                packageReferenceItemGroup.Add(new XElement(ns + "PackageReference",
-                    new XAttribute("Include", $"{packageReference.ID}"),
-                    new XAttribute("Version", $"{packageReference.Version}")));
+                var packageReferenceElement = new XElement(ns + "PackageReference",
+                    new XAttribute("Include", packageReference.ID));
+                if (packageReference.Version != null)
+                {
+                    packageReferenceElement.Add(new XAttribute("Version", packageReference.Version));
+                }
+                packageReferenceItemGroup.Add(packageReferenceElement);
             }
 
             foreach (TestPackageReference dotnetCliToolReference in DotNetCliToolReferences)