diff --git a/packages/compiler-cli/src/ngtsc/annotations/src/component.ts b/packages/compiler-cli/src/ngtsc/annotations/src/component.ts
index 0dfddae248..55c9597c9a 100644
--- a/packages/compiler-cli/src/ngtsc/annotations/src/component.ts
+++ b/packages/compiler-cli/src/ngtsc/annotations/src/component.ts
@@ -975,6 +975,7 @@ export class ComponentDecoratorHandler implements
       enableI18nLegacyMessageIdFormat: this.enableI18nLegacyMessageIdFormat,
       i18nNormalizeLineEndingsInICUs,
       isInline: template.isInline,
+      alwaysAttemptHtmlToR3AstConversion: this.usePoisonedData,
     });
 
     // Unfortunately, the primary parse of the template above may not contain accurate source map
@@ -1002,6 +1003,7 @@ export class ComponentDecoratorHandler implements
       i18nNormalizeLineEndingsInICUs,
       leadingTriviaChars: [],
       isInline: template.isInline,
+      alwaysAttemptHtmlToR3AstConversion: this.usePoisonedData,
     });
 
     return {
diff --git a/packages/compiler/src/render3/view/template.ts b/packages/compiler/src/render3/view/template.ts
index 88ad359364..4103a3f06b 100644
--- a/packages/compiler/src/render3/view/template.ts
+++ b/packages/compiler/src/render3/view/template.ts
@@ -2096,6 +2096,22 @@ export interface ParseTemplateOptions {
    * Whether the template was inline.
    */
   isInline?: boolean;
+
+  /**
+   * Whether to always attempt to convert the parsed HTML AST to an R3 AST, despite HTML or i18n
+   * Meta parse errors.
+   *
+   *
+   * This option is useful in the context of the language service, where we want to get as much
+   * information as possible, despite any errors in the HTML. As an example, a user may be adding
+   * a new tag and expecting autocomplete on that tag. In this scenario, the HTML is in an errored
+   * state, as there is an incomplete open tag. However, we're still able to convert the HTML AST
+   * nodes to R3 AST nodes in order to provide information for the language service.
+   *
+   * Note that even when `true` the HTML parse and i18n errors are still appended to the errors
+   * output, but this is done after converting the HTML AST to R3 AST.
+   */
+  alwaysAttemptHtmlToR3AstConversion?: boolean;
 }
 
 /**
@@ -2115,9 +2131,8 @@ export function parseTemplate(
       template, templateUrl,
       {leadingTriviaChars: LEADING_TRIVIA_CHARS, ...options, tokenizeExpansionForms: true});
 
-  if (parseResult.errors && parseResult.errors.length > 0) {
-    // TODO(ayazhafiz): we may not always want to bail out at this point (e.g. in
-    // the context of a language service).
+  if (!options.alwaysAttemptHtmlToR3AstConversion && parseResult.errors &&
+      parseResult.errors.length > 0) {
     return {
       interpolationConfig,
       preserveWhitespaces,
@@ -2143,7 +2158,8 @@ export function parseTemplate(
       enableI18nLegacyMessageIdFormat);
   const i18nMetaResult = i18nMetaVisitor.visitAllWithErrors(rootNodes);
 
-  if (i18nMetaResult.errors && i18nMetaResult.errors.length > 0) {
+  if (!options.alwaysAttemptHtmlToR3AstConversion && i18nMetaResult.errors &&
+      i18nMetaResult.errors.length > 0) {
     return {
       interpolationConfig,
       preserveWhitespaces,
@@ -2175,6 +2191,7 @@ export function parseTemplate(
 
   const {nodes, errors, styleUrls, styles, ngContentSelectors} =
       htmlAstToRender3Ast(rootNodes, bindingParser);
+  errors.push(...parseResult.errors, ...i18nMetaResult.errors);
 
   return {
     interpolationConfig,
diff --git a/packages/compiler/test/render3/r3_template_transform_spec.ts b/packages/compiler/test/render3/r3_template_transform_spec.ts
index cf1cfb40bf..d27e7e51d4 100644
--- a/packages/compiler/test/render3/r3_template_transform_spec.ts
+++ b/packages/compiler/test/render3/r3_template_transform_spec.ts
@@ -116,6 +116,19 @@ describe('R3 template transform', () => {
   });
 
   describe('Nodes without binding', () => {
+    it('should parse incomplete tags terminated by EOF', () => {
+      expectFromHtml('<a', true /* ignoreError */).toEqual([
+        ['Element', 'a'],
+      ]);
+    });
+
+    it('should parse incomplete tags terminated by another tag', () => {
+      expectFromHtml('<a <span></span>', true /* ignoreError */).toEqual([
+        ['Element', 'a'],
+        ['Element', 'span'],
+      ]);
+    });
+
     it('should parse text nodes', () => {
       expectFromHtml('a').toEqual([
         ['Text', 'a'],
diff --git a/packages/language-service/ivy/test/completions_spec.ts b/packages/language-service/ivy/test/completions_spec.ts
index eac4d9816e..62d4139dec 100644
--- a/packages/language-service/ivy/test/completions_spec.ts
+++ b/packages/language-service/ivy/test/completions_spec.ts
@@ -353,6 +353,23 @@ describe('completions', () => {
       expect(ts.displayPartsToString(details.documentation!)).toEqual('This is another component.');
     });
 
+    it('should return completions for an incomplete tag', () => {
+      const OTHER_CMP = {
+        'OtherCmp': `
+            /** This is another component. */
+            @Component({selector: 'other-cmp', template: 'unimportant'})
+            export class OtherCmp {}
+          `,
+      };
+      const {templateFile} = setup(`<other`, '', OTHER_CMP);
+      templateFile.moveCursorToText('<other¦');
+
+      const completions = templateFile.getCompletionsAtPosition();
+      expectContain(
+          completions, unsafeCastDisplayInfoKindToScriptElementKind(DisplayInfoKind.COMPONENT),
+          ['other-cmp']);
+    });
+
     it('should return completions with a blank open tag', () => {
       const OTHER_CMP = {
         'OtherCmp': `
@@ -397,6 +414,10 @@ describe('completions', () => {
 
       const completions = templateFile.getCompletionsAtPosition();
       expect(completions).toBeUndefined();
+
+
+      const details = templateFile.getCompletionEntryDetails('other-cmp')!;
+      expect(details).toBeUndefined();
     });
 
     describe('element attribute scope', () => {
diff --git a/packages/language-service/ivy/test/diagnostic_spec.ts b/packages/language-service/ivy/test/diagnostic_spec.ts
index 97ccf9dc1d..5288e06814 100644
--- a/packages/language-service/ivy/test/diagnostic_spec.ts
+++ b/packages/language-service/ivy/test/diagnostic_spec.ts
@@ -19,7 +19,7 @@ describe('getSemanticDiagnostics', () => {
     env = LanguageServiceTestEnv.setup();
   });
 
-  it('should not produce error for a minimal component defintion', () => {
+  it('should not produce error for a minimal component definition', () => {
     const files = {
       'app.ts': `
       import {Component, NgModule} from '@angular/core';
@@ -124,6 +124,34 @@ describe('getSemanticDiagnostics', () => {
             `Parser Error: Bindings cannot contain assignments at column 8 in [{{nope = true}}]`);
   });
 
+  it('reports html parse errors along with typecheck errors as diagnostics', () => {
+    const files = {
+      'app.ts': `
+      import {Component, NgModule} from '@angular/core';
+
+      @Component({
+        templateUrl: './app.html'
+      })
+      export class AppComponent {
+        nope = false;
+      }
+    `,
+      'app.html': '<dne'
+    };
+
+    const project = createModuleAndProjectWithDeclarations(env, 'test', files);
+    const diags = project.getDiagnosticsForFile('app.html');
+    expect(diags.length).toBe(2);
+
+    expect(diags[0].category).toBe(ts.DiagnosticCategory.Error);
+    expect(diags[0].file?.fileName).toBe('/test/app.html');
+    expect(diags[0].messageText).toContain(`'dne' is not a known element`);
+
+    expect(diags[1].category).toBe(ts.DiagnosticCategory.Error);
+    expect(diags[1].file?.fileName).toBe('/test/app.html');
+    expect(diags[1].messageText).toContain(`Opening tag "dne" not terminated.`);
+  });
+
   it('should report parse errors of components defined in the same ts file', () => {
     const files = {
       'app.ts': `
diff --git a/packages/language-service/ivy/test/legacy/template_target_spec.ts b/packages/language-service/ivy/test/legacy/template_target_spec.ts
index 73457a9d2e..01623e9d7c 100644
--- a/packages/language-service/ivy/test/legacy/template_target_spec.ts
+++ b/packages/language-service/ivy/test/legacy/template_target_spec.ts
@@ -35,12 +35,23 @@ function parse(template: string): ParseResult {
       // `ComponentDecoratorHandler._parseTemplate`.
       leadingTriviaChars: [],
       preserveWhitespaces: true,
+      alwaysAttemptHtmlToR3AstConversion: true,
     }),
     position,
   };
 }
 
 describe('getTargetAtPosition for template AST', () => {
+  it('should locate incomplete tag', () => {
+    const {errors, nodes, position} = parse(`<div¦`);
+    expect(errors?.length).toBe(1);
+    expect(errors![0].msg).toContain('Opening tag "div" not terminated.');
+    const {context} = getTargetAtPosition(nodes, position)!;
+    const {node} = context as SingleNodeTarget;
+    expect(isTemplateNode(node!)).toBe(true);
+    expect(node).toBeInstanceOf(t.Element);
+  });
+
   it('should locate element in opening tag', () => {
     const {errors, nodes, position} = parse(`<di¦v></div>`);
     expect(errors).toBe(null);