diff --git a/README.md b/README.md
index 6115cba..cc762c3 100644
--- a/README.md
+++ b/README.md
@@ -226,7 +226,8 @@ bundle.toString();
 //   console.log( answer );
 // }());
 
-// options are as per `s.generateMap()` above
+// options are as per `s.generateMap()` above except that `options.includeContent` can also
+// be a function with the signature `function(source: { filename: string, content: string }): boolean`
 var map = bundle.generateMap({
   file: 'bundle.js',
   includeContent: true,
diff --git a/index.d.ts b/index.d.ts
index 251701c..f390ed3 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -10,6 +10,16 @@ export interface SourceMapOptions {
   includeContent: boolean;
 }
 
+
+export interface BundledSourceFileRecord {
+  filename: string | null;
+  content: string;
+}
+
+export interface BundleSourceMapOptions extends SourceMapOptions {
+  includeContent: boolean | ((source: BundledSourceFileRecord) => boolean);
+}
+
 export type SourceMapSegment =
   | [number]
   | [number, number, number, number]
@@ -42,8 +52,8 @@ export class Bundle {
   addSource(source: MagicString | { filename?: string, content: MagicString }): Bundle;
   append(str: string, options?: BundleOptions): Bundle;
   clone(): Bundle;
-  generateMap(options?: Partial<SourceMapOptions>): SourceMap;
-  generateDecodedMap(options?: Partial<SourceMapOptions>): DecodedSourceMap;
+  generateMap(options?: Partial<BundleSourceMapOptions>): SourceMap;
+  generateDecodedMap(options?: Partial<BundleSourceMapOptions>): DecodedSourceMap;
   getIndentString(): string;
   indent(indentStr?: string): Bundle;
   indentExclusionRanges: ExclusionRange | Array<ExclusionRange>;
diff --git a/src/Bundle.js b/src/Bundle.js
index 76fa317..ff7609c 100644
--- a/src/Bundle.js
+++ b/src/Bundle.js
@@ -147,7 +147,9 @@ export default class Bundle {
 				return options.file ? getRelativePath(options.file, source.filename) : source.filename;
 			}),
 			sourcesContent: this.uniqueSources.map(source => {
-				return options.includeContent ? source.content : null;
+				const includeContent = typeof options.includeContent === 'function' ? options.includeContent(source) : options.includeContent;
+
+				return includeContent ? source.content : null;
 			}),
 			names,
 			mappings: mappings.raw
diff --git a/test/MagicString.Bundle.js b/test/MagicString.Bundle.js
index 05883e9..07d583e 100644
--- a/test/MagicString.Bundle.js
+++ b/test/MagicString.Bundle.js
@@ -495,6 +495,32 @@ var template = (function () {
 				column: 16
 			});
 		});
+
+		it('supports a function for includeContent', () => {
+			const b = new MagicString.Bundle();
+
+			const files = {
+				'one.js': new MagicString('function one () {}', { filename: 'one.js' }),
+				'two.js': new MagicString('function two () {}', { filename: 'two.js' }),
+			};
+
+			b.addSource(files['one.js']);
+			b.addSource(files['two.js']);
+
+			const map = b.generateMap({
+				file: 'output.js',
+				source: 'input.js',
+				includeContent(source) {
+					assert.ok(files[source.filename]);
+					assert.equal(files[source.filename].original, source.content);
+
+					return source.filename === 'one.js';
+				}
+			});
+
+			assert.equal(map.sourcesContent[0], files['one.js'].original);
+			assert.equal(map.sourcesContent[1], null);
+		});
 	});
 
 	describe('indent', () => {