diff --git a/src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorIRLoweringPhase.cs b/src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorIRLoweringPhase.cs
index 99eae8977f..2582765413 100644
--- a/src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorIRLoweringPhase.cs
+++ b/src/Microsoft.AspNetCore.Razor.Evolution/DefaultRazorIRLoweringPhase.cs
@@ -390,9 +390,15 @@ namespace Microsoft.AspNetCore.Razor.Evolution
                     Source = BuildSourceSpanFromNode(block)
                 });
 
+                var tagName = tagHelperBlock.TagName;
+                if (tagHelperBlock.Descriptors.First().Prefix != null)
+                {
+                    tagName = tagName.Substring(tagHelperBlock.Descriptors.First().Prefix.Length);
+                }
+
                 _builder.Push(new InitializeTagHelperStructureIRNode()
                 {
-                    TagName = tagHelperBlock.TagName,
+                    TagName = tagName,
                     TagMode = tagHelperBlock.TagMode
                 });
             }
diff --git a/src/Microsoft.AspNetCore.Razor.Evolution/RazorCSharpDocument.cs b/src/Microsoft.AspNetCore.Razor.Evolution/RazorCSharpDocument.cs
index b021ca2039..3c5d162581 100644
--- a/src/Microsoft.AspNetCore.Razor.Evolution/RazorCSharpDocument.cs
+++ b/src/Microsoft.AspNetCore.Razor.Evolution/RazorCSharpDocument.cs
@@ -12,6 +12,6 @@ namespace Microsoft.AspNetCore.Razor.Evolution
 
         internal IReadOnlyList<LineMapping> LineMappings { get; set; }
 
-        internal IReadOnlyList<RazorError> Diagnostics { get; set; }
+        public IReadOnlyList<RazorError> Diagnostics { get; set; }
     }
 }
diff --git a/test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRLoweringPhaseIntegrationTest.cs b/test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRLoweringPhaseIntegrationTest.cs
index 3ca28364e8..dd4267e18b 100644
--- a/test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRLoweringPhaseIntegrationTest.cs
+++ b/test/Microsoft.AspNetCore.Razor.Evolution.Test/Intermediate/DefaultRazorIRLoweringPhaseIntegrationTest.cs
@@ -194,6 +194,49 @@ namespace Microsoft.AspNetCore.Razor.Evolution.Intermediate
                 });
         }
 
+        [Fact]
+        public void Lower_TagHelpers_WithPrefix()
+        {
+            // Arrange
+            var codeDocument = TestRazorCodeDocument.Create(@"@addTagHelper *, TestAssembly
+@tagHelperPrefix cool:
+<cool:span val=""@Hello World""></cool:span>");
+            var tagHelpers = new[]
+            {
+                new TagHelperDescriptor
+                {
+                    TagName = "span",
+                    TypeName = "SpanTagHelper",
+                    AssemblyName = "TestAssembly",
+                }
+            };
+
+            // Act
+            var irDocument = Lower(codeDocument, tagHelpers: tagHelpers);
+
+            // Assert
+            Children(irDocument,
+                n => Checksum(n),
+                n => Using("System", n),
+                n => Using(typeof(Task).Namespace, n),
+                n => TagHelperFieldDeclaration(n, "SpanTagHelper"),
+                n =>
+                {
+                    var tagHelperNode = Assert.IsType<TagHelperIRNode>(n);
+                    Children(
+                        tagHelperNode,
+                        c => TagHelperStructure("span", TagMode.StartTagAndEndTag, c), // Note: this is span not cool:span
+                        c => Assert.IsType<CreateTagHelperIRNode>(c),
+                        c => TagHelperHtmlAttribute(
+                            "val",
+                            HtmlAttributeValueStyle.DoubleQuotes,
+                            c,
+                            v => CSharpAttributeValue(string.Empty, "Hello", v),
+                            v => LiteralAttributeValue(" ", "World", v)),
+                        c => Assert.IsType<ExecuteTagHelpersIRNode>(c));
+                });
+        }
+
         [Fact]
         public void Lower_TagHelper_InSection()
         {
diff --git a/test/Microsoft.AspNetCore.Razor.Evolution.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.codegen.cs b/test/Microsoft.AspNetCore.Razor.Evolution.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.codegen.cs
index b25fe00f74..266086a73a 100644
--- a/test/Microsoft.AspNetCore.Razor.Evolution.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.codegen.cs
+++ b/test/Microsoft.AspNetCore.Razor.Evolution.Test/TestFiles/IntegrationTests/CodeGenerationIntegrationTest/BasicTagHelpers_Prefixed_Runtime.codegen.cs
@@ -33,9 +33,9 @@ namespace Microsoft.AspNetCore.Razor.Evolution.IntegrationTests.TestFiles
         public async System.Threading.Tasks.Task ExecuteAsync()
         {
             WriteLiteral("\r\n<THSdiv class=\"randomNonTagHelperAttribute\">\r\n    ");
-            __tagHelperExecutionContext = __tagHelperScopeManager.Begin("THSp", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagAndEndTag, "test", async() => {
+            __tagHelperExecutionContext = __tagHelperScopeManager.Begin("p", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagAndEndTag, "test", async() => {
                 WriteLiteral("\r\n        <p></p>\r\n        <input type=\"text\">\r\n        ");
-                __tagHelperExecutionContext = __tagHelperScopeManager.Begin("THSinput", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagOnly, "test", async() => {
+                __tagHelperExecutionContext = __tagHelperScopeManager.Begin("input", global::Microsoft.AspNetCore.Razor.TagHelpers.TagMode.StartTagOnly, "test", async() => {
                 }
                 );
                 __TestNamespace_InputTagHelper = CreateTagHelper<global::TestNamespace.InputTagHelper>();