--- a/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/HtmlDoclet.java	Thu May 24 15:23:28 2018 +0100
+++ b/src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/HtmlDoclet.java	Thu May 24 20:34:17 2018 +0530
@@ -184,7 +184,7 @@
         DocFile f;
         if (configuration.stylesheetfile.length() == 0) {
             f = DocFile.createFileForOutput(configuration, DocPaths.STYLESHEET);
-            f.copyResource(DocPaths.RESOURCES.resolve(DocPaths.STYLESHEET), false, true);
+            f.copyResource(DocPaths.RESOURCES.resolve(DocPaths.STYLESHEET), true, true);
         }
         f = DocFile.createFileForOutput(configuration, DocPaths.JAVASCRIPT);
         f.copyResource(DocPaths.RESOURCES.resolve(DocPaths.JAVASCRIPT), true, true);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/jdk/javadoc/doclet/testStylesheetOverwrite/TestStylesheetOverwrite.java	Thu May 24 20:34:17 2018 +0530
@@ -0,0 +1,80 @@
+/* * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug      8196913
+ * @summary  javadoc does not (over)write stylesheet.css
+ * @library  /tools/lib ../lib
+ * @modules jdk.javadoc/jdk.javadoc.internal.tool
+ * @build    JavadocTester toolbox.ToolBox builder.ClassBuilder
+ * @run main TestStylesheetOverwrite
+ */
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.List;
+
+import builder.ClassBuilder;
+import toolbox.ToolBox;
+
+public class TestStylesheetOverwrite extends JavadocTester {
+    final ToolBox tb;
+
+    public static void main(String... args) throws Exception {
+        TestStylesheetOverwrite tester = new TestStylesheetOverwrite();
+        tester.runTests(m -> new Object[]{Paths.get(m.getName())});
+    }
+
+    TestStylesheetOverwrite() {
+        tb = new ToolBox();
+    }
+
+    @Test
+    void testStylesheetFile(Path base) throws Exception {
+        Path srcDir = base.resolve("src");
+        createTestClass(srcDir);
+
+        Path outDir = base.resolve("out");
+
+        Files.createDirectory(outDir);
+        Path stylesheet = outDir.resolve("stylesheet.css");
+        Files.createFile(stylesheet);
+        Files.write(stylesheet, List.of("/* custom stylesheet */"));
+
+        setOutputDirectoryCheck(DirectoryCheck.NONE);
+
+        javadoc("-d", outDir.toString(),
+                "-sourcepath", srcDir.toString(),
+                "pkg");
+
+        checkExit(Exit.OK);
+        checkOutput("stylesheet.css", true, "Javadoc style sheet");
+    }
+
+    void createTestClass(Path srcDir) throws Exception {
+        new ClassBuilder(tb, "pkg.A")
+                .setModifiers("public", "class")
+                .write(srcDir);
+    }
+}