diff --git a/packages/compiler-cli/ngcc/src/analysis/decoration_analyzer.ts b/packages/compiler-cli/ngcc/src/analysis/decoration_analyzer.ts
index 1fc2a48d9f..b8bd0b9634 100644
--- a/packages/compiler-cli/ngcc/src/analysis/decoration_analyzer.ts
+++ b/packages/compiler-cli/ngcc/src/analysis/decoration_analyzer.ts
@@ -137,6 +137,7 @@ export class DecorationAnalyzer {
   analyzeProgram(): DecorationAnalyses {
     const decorationAnalyses = new DecorationAnalyses();
     const analyzedFiles = this.program.getSourceFiles()
+                              .filter(sourceFile => !sourceFile.isDeclarationFile)
                               .filter(sourceFile => isWithinPackage(this.packagePath, sourceFile))
                               .map(sourceFile => this.analyzeFile(sourceFile))
                               .filter(isDefined);
diff --git a/packages/compiler-cli/ngcc/test/analysis/decoration_analyzer_spec.ts b/packages/compiler-cli/ngcc/test/analysis/decoration_analyzer_spec.ts
index 0ecba3079d..4f057ec35b 100644
--- a/packages/compiler-cli/ngcc/test/analysis/decoration_analyzer_spec.ts
+++ b/packages/compiler-cli/ngcc/test/analysis/decoration_analyzer_spec.ts
@@ -11,7 +11,7 @@ import {FatalDiagnosticError, makeDiagnostic} from '../../../src/ngtsc/diagnosti
 import {absoluteFrom, getFileSystem, getSourceFileOrError} from '../../../src/ngtsc/file_system';
 import {TestFile, runInEachFileSystem} from '../../../src/ngtsc/file_system/testing';
 import {ClassDeclaration, Decorator} from '../../../src/ngtsc/reflection';
-import {DecoratorHandler, DetectResult} from '../../../src/ngtsc/transform';
+import {AnalysisOutput, CompileResult, DecoratorHandler, DetectResult, HandlerPrecedence} from '../../../src/ngtsc/transform';
 import {loadFakeCore, loadTestFiles} from '../../../test/helpers';
 import {DecorationAnalyzer} from '../../src/analysis/decoration_analyzer';
 import {NgccReferencesRegistry} from '../../src/analysis/ngcc_references_registry';
@@ -392,6 +392,29 @@ runInEachFileSystem(() => {
              expect(diagnosticLogs[1]).toEqual(jasmine.objectContaining({code: -999998}));
            });
       });
+
+      describe('declaration files', () => {
+        it('should not run decorator handlers against declaration files', () => {
+          class FakeDecoratorHandler implements DecoratorHandler<{}|null, unknown, unknown> {
+            name = 'FakeDecoratorHandler';
+            precedence = HandlerPrecedence.PRIMARY;
+
+            detect(): undefined { throw new Error('detect should not have been called'); }
+            analyze(): AnalysisOutput<unknown> {
+              throw new Error('analyze should not have been called');
+            }
+            compile(): CompileResult { throw new Error('compile should not have been called'); }
+          }
+
+          const analyzer = setUpAnalyzer([{
+            name: _('/node_modules/test-package/index.d.ts'),
+            contents: 'export declare class SomeDirective {}',
+          }]);
+          analyzer.handlers = [new FakeDecoratorHandler()];
+          result = analyzer.analyzeProgram();
+          expect(result.size).toBe(0);
+        });
+      });
     });
   });
 });
diff --git a/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts b/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts
index c9d51d2d6e..4439c12ea8 100644
--- a/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts
+++ b/packages/compiler-cli/src/ngtsc/annotations/src/directive.ts
@@ -55,10 +55,6 @@ export class DirectiveDecoratorHandler implements
 
   detect(node: ClassDeclaration, decorators: Decorator[]|null):
       DetectResult<Decorator|null>|undefined {
-    // Compiling declaration files is invalid.
-    if (node.getSourceFile().isDeclarationFile) {
-      return undefined;
-    }
     // If the class is undecorated, check if any of the fields have Angular decorators or lifecycle
     // hooks, and if they do, label the class as an abstract directive.
     if (!decorators) {
diff --git a/packages/compiler-cli/src/ngtsc/incremental/index.ts b/packages/compiler-cli/src/ngtsc/incremental/index.ts
index e4a3ff8580..506dd2bbfe 100644
--- a/packages/compiler-cli/src/ngtsc/incremental/index.ts
+++ b/packages/compiler-cli/src/ngtsc/incremental/index.ts
@@ -6,4 +6,5 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+export {NOOP_INCREMENTAL_BUILD} from './src/noop';
 export {IncrementalDriver} from './src/state';
diff --git a/packages/compiler-cli/src/ngtsc/incremental/src/noop.ts b/packages/compiler-cli/src/ngtsc/incremental/src/noop.ts
new file mode 100644
index 0000000000..3ad486d2c4
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/incremental/src/noop.ts
@@ -0,0 +1,13 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {IncrementalBuild} from '../api';
+
+export const NOOP_INCREMENTAL_BUILD: IncrementalBuild<any> = {
+  priorWorkFor: () => null
+};
diff --git a/packages/compiler-cli/src/ngtsc/transform/src/compilation.ts b/packages/compiler-cli/src/ngtsc/transform/src/compilation.ts
index 84d32fc1d5..a47b59a0df 100644
--- a/packages/compiler-cli/src/ngtsc/transform/src/compilation.ts
+++ b/packages/compiler-cli/src/ngtsc/transform/src/compilation.ts
@@ -103,6 +103,11 @@ export class TraitCompiler {
   private analyze(sf: ts.SourceFile, preanalyze: false): void;
   private analyze(sf: ts.SourceFile, preanalyze: true): Promise<void>|undefined;
   private analyze(sf: ts.SourceFile, preanalyze: boolean): Promise<void>|undefined {
+    // We shouldn't analyze declaration files.
+    if (sf.isDeclarationFile) {
+      return undefined;
+    }
+
     // analyze() really wants to return `Promise<void>|void`, but TypeScript cannot narrow a return
     // type of 'void', so `undefined` is used instead.
     const promises: Promise<void>[] = [];
diff --git a/packages/compiler-cli/src/ngtsc/transform/test/BUILD.bazel b/packages/compiler-cli/src/ngtsc/transform/test/BUILD.bazel
new file mode 100644
index 0000000000..9346799eff
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/transform/test/BUILD.bazel
@@ -0,0 +1,32 @@
+load("//tools:defaults.bzl", "jasmine_node_test", "ts_library")
+
+package(default_visibility = ["//visibility:public"])
+
+ts_library(
+    name = "test_lib",
+    testonly = True,
+    srcs = glob([
+        "**/*.ts",
+    ]),
+    deps = [
+        "//packages:types",
+        "//packages/compiler",
+        "//packages/compiler-cli/src/ngtsc/file_system",
+        "//packages/compiler-cli/src/ngtsc/file_system/testing",
+        "//packages/compiler-cli/src/ngtsc/incremental",
+        "//packages/compiler-cli/src/ngtsc/perf",
+        "//packages/compiler-cli/src/ngtsc/reflection",
+        "//packages/compiler-cli/src/ngtsc/testing",
+        "//packages/compiler-cli/src/ngtsc/transform",
+        "@npm//typescript",
+    ],
+)
+
+jasmine_node_test(
+    name = "test",
+    bootstrap = ["angular/tools/testing/init_node_no_angular_spec.js"],
+    deps = [
+        ":test_lib",
+        "//tools/testing:node_no_angular",
+    ],
+)
diff --git a/packages/compiler-cli/src/ngtsc/transform/test/compilation_spec.ts b/packages/compiler-cli/src/ngtsc/transform/test/compilation_spec.ts
new file mode 100644
index 0000000000..8608e4364f
--- /dev/null
+++ b/packages/compiler-cli/src/ngtsc/transform/test/compilation_spec.ts
@@ -0,0 +1,50 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {absoluteFrom} from '../../file_system';
+import {runInEachFileSystem} from '../../file_system/testing';
+import {NOOP_INCREMENTAL_BUILD} from '../../incremental';
+import {NOOP_PERF_RECORDER} from '../../perf';
+import {ClassDeclaration, TypeScriptReflectionHost} from '../../reflection';
+import {makeProgram} from '../../testing';
+import {DtsTransformRegistry, TraitCompiler} from '../../transform';
+import {AnalysisOutput, CompileResult, DecoratorHandler, HandlerPrecedence} from '../src/api';
+
+runInEachFileSystem(() => {
+  describe('TraitCompiler', () => {
+    let _: typeof absoluteFrom;
+    beforeEach(() => _ = absoluteFrom);
+
+    it('should not run decoration handlers against declaration files', () => {
+      class FakeDecoratorHandler implements DecoratorHandler<{}|null, unknown, unknown> {
+        name = 'FakeDecoratorHandler';
+        precedence = HandlerPrecedence.PRIMARY;
+
+        detect(): undefined { throw new Error('detect should not have been called'); }
+        analyze(): AnalysisOutput<unknown> {
+          throw new Error('analyze should not have been called');
+        }
+        compile(): CompileResult { throw new Error('compile should not have been called'); }
+      }
+
+      const {program} = makeProgram([{
+        name: _('/lib.d.ts'),
+        contents: `export declare class SomeDirective {}`,
+      }]);
+      const checker = program.getTypeChecker();
+      const reflectionHost = new TypeScriptReflectionHost(checker);
+      const compiler = new TraitCompiler(
+          [new FakeDecoratorHandler()], reflectionHost, NOOP_PERF_RECORDER, NOOP_INCREMENTAL_BUILD,
+          true, new DtsTransformRegistry());
+      const sourceFile = program.getSourceFile('lib.d.ts') !;
+      const analysis = compiler.analyzeSync(sourceFile);
+
+      expect(sourceFile.isDeclarationFile).toBe(true);
+      expect(analysis).toBeFalsy();
+    });
+  });
+});