diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptions.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptions.java
index dfe78002a78b09..507cec366e2c8f 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptions.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptions.java
@@ -32,6 +32,7 @@ public class TurbineOptions {
   private final ImmutableList<String> sources;
   private final ImmutableList<String> processorPath;
   private final ImmutableSet<String> processors;
+  private final ImmutableSet<String> blacklistedProcessors;
   private final String tempDir;
   private final ImmutableList<String> sourceJars;
   private final Optional<String> outputDeps;
@@ -50,6 +51,7 @@ private TurbineOptions(
       ImmutableList<String> sources,
       ImmutableList<String> processorPath,
       ImmutableSet<String> processors,
+      ImmutableSet<String> blacklistedProcessors,
       String tempDir,
       ImmutableList<String> sourceJars,
       @Nullable String outputDeps,
@@ -66,6 +68,8 @@ private TurbineOptions(
     this.sources = checkNotNull(sources, "sources must not be null");
     this.processorPath = checkNotNull(processorPath, "processorPath must not be null");
     this.processors = checkNotNull(processors, "processors must not be null");
+    this.blacklistedProcessors =
+        checkNotNull(blacklistedProcessors, "blacklistedProcessors must not be null");
     this.tempDir = checkNotNull(tempDir, "tempDir must not be null");
     this.sourceJars = checkNotNull(sourceJars, "sourceJars must not be null");
     this.outputDeps = Optional.fromNullable(outputDeps);
@@ -115,6 +119,14 @@ public ImmutableSet<String> processors() {
     return processors;
   }
 
+  /**
+   * Annotation processors that require tree pruning to be disabled, for example because they use
+   * internal compiler APIs to inspect information that would be removed during pruning.
+   */
+  public ImmutableSet<String> blacklistedProcessors() {
+    return blacklistedProcessors;
+  }
+
   /** Source jars for compilation. */
   public ImmutableList<String> sourceJars() {
     return sourceJars;
@@ -176,6 +188,7 @@ public static class Builder {
     private final ImmutableList.Builder<String> sources = ImmutableList.builder();
     private final ImmutableList.Builder<String> processorPath = ImmutableList.builder();
     private final ImmutableSet.Builder<String> processors = ImmutableSet.builder();
+    private final ImmutableSet.Builder<String> blacklistedProcessors = ImmutableSet.builder();
     private String tempDir;
     private final ImmutableList.Builder<String> sourceJars = ImmutableList.builder();
     private final ImmutableList.Builder<String> bootClassPath = ImmutableList.builder();
@@ -197,6 +210,7 @@ public TurbineOptions build() {
           sources.build(),
           processorPath.build(),
           processors.build(),
+          blacklistedProcessors.build(),
           tempDir,
           sourceJars.build(),
           outputDeps,
@@ -244,6 +258,11 @@ public Builder addProcessors(Iterable<String> processors) {
       return this;
     }
 
+    public Builder addBlacklistedProcessors(Iterable<String> processors) {
+      this.blacklistedProcessors.addAll(processors);
+      return this;
+    }
+
     public Builder setTempDir(String tempDir) {
       this.tempDir = tempDir;
       return this;
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptionsParser.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptionsParser.java
index 2c8d87ea1c9f33..9e0ada2e2179c0 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptionsParser.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/TurbineOptionsParser.java
@@ -33,15 +33,24 @@
 public class TurbineOptionsParser {
 
   /**
-   * Parses a list of command-line options into a {@link TurbineOptions}, expanding any
-   * {@code @params} files.
+   * Parses command line options into {@link TurbineOptions}, expanding any {@code @params}
+   * files.
    */
   public static TurbineOptions parse(Iterable<String> args) throws IOException {
+    TurbineOptions.Builder builder = TurbineOptions.builder();
+    parse(builder, args);
+    return builder.build();
+  }
+
+  /**
+   * Parses command line options into a {@link TurbineOptions.Builder}, expanding any
+   * {@code @params} files.
+   */
+  public static void parse(TurbineOptions.Builder builder, Iterable<String> args)
+      throws IOException {
     Deque<String> argumentDeque = new ArrayDeque<>();
     expandParamsFiles(argumentDeque, args);
-    TurbineOptions.Builder builder = TurbineOptions.builder();
     parse(builder, argumentDeque);
-    return builder.build();
   }
 
   private static final Splitter ARG_SPLITTER =
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/BUILD b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/BUILD
index b62b34b04b392d..9e3e6cbeead2a4 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/BUILD
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/BUILD
@@ -65,6 +65,7 @@ java_library(
     name = "javac_turbine_java_compiler",
     srcs = ["JavacTurbineJavaCompiler.java"],
     deps = [
+        ":javac_turbine_compile_request",
         ":tree_pruner",
         "//src/java_tools/buildjar/java/com/google/devtools/build/buildjar/javac/plugins:dependency",
         "//third_party:jsr305",
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbine.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbine.java
index 0b161158d7e8ac..0ec92b3610e3d1 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbine.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbine.java
@@ -24,6 +24,7 @@
 import com.google.devtools.build.buildjar.javac.plugins.dependency.StrictJavaDepsPlugin;
 import com.google.devtools.build.java.turbine.TurbineOptions;
 import com.google.devtools.build.java.turbine.TurbineOptionsParser;
+import com.google.devtools.build.java.turbine.javac.JavacTurbineCompileRequest.Prune;
 import com.google.devtools.build.java.turbine.javac.ZipOutputFileManager.OutputFileObject;
 
 import com.sun.tools.javac.util.Context;
@@ -78,7 +79,7 @@ public static Result compile(TurbineOptions turbineOptions) throws IOException {
   }
 
   /** A header compilation result. */
-  enum Result {
+  public enum Result {
     /** The compilation succeeded with the reduced classpath optimization. */
     OK_WITH_REDUCED_CLASSPATH(true),
 
@@ -94,11 +95,11 @@ private Result(boolean ok) {
       this.ok = ok;
     }
 
-    boolean ok() {
+    public boolean ok() {
       return ok;
     }
 
-    int exitCode() {
+    public int exitCode() {
       return ok ? 0 : 1;
     }
   }
@@ -156,6 +157,11 @@ Result compile() throws IOException {
             .setBootClassPath(asPaths(turbineOptions.bootClassPath()))
             .setProcessorClassPath(processorpath);
 
+    if (!Collections.disjoint(
+        turbineOptions.processors(), turbineOptions.blacklistedProcessors())) {
+      requestBuilder.setPrune(Prune.NO);
+    }
+
     StrictJavaDeps strictDepsMode = StrictJavaDeps.valueOf(turbineOptions.strictDepsMode());
 
     DependencyModule dependencyModule = buildDependencyModule(turbineOptions, strictDepsMode);
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompileRequest.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompileRequest.java
index 68f99fe9d6dee5..284d2e2083ca3c 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompileRequest.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompileRequest.java
@@ -14,8 +14,11 @@
 
 package com.google.devtools.build.java.turbine.javac;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.buildjar.javac.plugins.dependency.StrictJavaDepsPlugin;
+import com.google.devtools.build.java.turbine.javac.JavacTurbineCompileRequest.Prune;
 
 import java.nio.file.Path;
 
@@ -24,23 +27,31 @@
 /** The input to a {@link JavacTurbineCompiler} compilation. */
 class JavacTurbineCompileRequest {
 
+  enum Prune {
+    YES,
+    NO
+  }
+
   private final ImmutableList<Path> classPath;
   private final ImmutableList<Path> bootClassPath;
   private final ImmutableList<Path> processorClassPath;
   private final ImmutableList<String> javacOptions;
   @Nullable private final StrictJavaDepsPlugin strictJavaDepsPlugin;
+  private final Prune prune;
 
   JavacTurbineCompileRequest(
       ImmutableList<Path> classPath,
       ImmutableList<Path> bootClassPath,
       ImmutableList<Path> processorClassPath,
       ImmutableList<String> javacOptions,
-      @Nullable StrictJavaDepsPlugin strictJavaDepsPlugin) {
-    this.classPath = classPath;
-    this.bootClassPath = bootClassPath;
-    this.processorClassPath = processorClassPath;
-    this.javacOptions = javacOptions;
+      @Nullable StrictJavaDepsPlugin strictJavaDepsPlugin,
+      Prune prune) {
+    this.classPath = checkNotNull(classPath);
+    this.bootClassPath = checkNotNull(bootClassPath);
+    this.processorClassPath = checkNotNull(processorClassPath);
+    this.javacOptions = checkNotNull(javacOptions);
     this.strictJavaDepsPlugin = strictJavaDepsPlugin;
+    this.prune = checkNotNull(prune);
   }
 
   /** The class path; correspond's to javac -classpath. */
@@ -71,6 +82,11 @@ StrictJavaDepsPlugin strictJavaDepsPlugin() {
     return strictJavaDepsPlugin;
   }
 
+  /** Whether to perform a relaxed header-only compilation. */
+  Prune prune() {
+    return prune;
+  }
+
   static JavacTurbineCompileRequest.Builder builder() {
     return new Builder();
   }
@@ -81,12 +97,13 @@ static class Builder {
     private ImmutableList<Path> processorClassPath;
     private ImmutableList<String> javacOptions;
     @Nullable private StrictJavaDepsPlugin strictDepsPlugin;
+    private Prune prune = Prune.YES;
 
     private Builder() {}
 
     JavacTurbineCompileRequest build() {
       return new JavacTurbineCompileRequest(
-          classPath, bootClassPath, processorClassPath, javacOptions, strictDepsPlugin);
+          classPath, bootClassPath, processorClassPath, javacOptions, strictDepsPlugin, prune);
     }
 
     Builder setClassPath(ImmutableList<Path> classPath) {
@@ -113,5 +130,10 @@ Builder setStrictDepsPlugin(@Nullable StrictJavaDepsPlugin strictDepsPlugin) {
       this.strictDepsPlugin = strictDepsPlugin;
       return this;
     }
+
+    Builder setPrune(Prune prune) {
+      this.prune = prune;
+      return this;
+    }
   }
 }
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompiler.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompiler.java
index 0a59323cc8f98e..0718ec5968b425 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompiler.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineCompiler.java
@@ -16,6 +16,7 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.buildjar.javac.plugins.dependency.StrictJavaDepsPlugin;
+import com.google.devtools.build.java.turbine.javac.JavacTurbineCompileRequest.Prune;
 import com.google.devtools.build.java.turbine.javac.JavacTurbineCompileResult.Status;
 import com.google.devtools.build.java.turbine.javac.ZipOutputFileManager.OutputFileObject;
 
@@ -50,7 +51,7 @@ static JavacTurbineCompileResult compile(JavacTurbineCompileRequest request) thr
 
     try (PrintWriter pw = new PrintWriter(sw)) {
       ZipOutputFileManager.preRegister(context, files);
-      setupContext(context, request.strictJavaDepsPlugin());
+      setupContext(context, request.strictJavaDepsPlugin(), request.prune());
       CacheFSInfo.preRegister(context);
 
       context.put(Log.outKey, pw);
@@ -93,7 +94,7 @@ static JavacTurbineCompileResult compile(JavacTurbineCompileRequest request) thr
     return new JavacTurbineCompileResult(ImmutableMap.copyOf(files), status, sw, context);
   }
 
-  static void setupContext(Context context, @Nullable StrictJavaDepsPlugin sjd) {
-    JavacTurbineJavaCompiler.preRegister(context, sjd);
+  static void setupContext(Context context, @Nullable StrictJavaDepsPlugin sjd, Prune prune) {
+    JavacTurbineJavaCompiler.preRegister(context, sjd, prune);
   }
 }
diff --git a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineJavaCompiler.java b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineJavaCompiler.java
index 874b1811a49930..d49863a4235cf2 100644
--- a/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineJavaCompiler.java
+++ b/src/java_tools/buildjar/java/com/google/devtools/build/java/turbine/javac/JavacTurbineJavaCompiler.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.java.turbine.javac;
 
 import com.google.devtools.build.buildjar.javac.plugins.dependency.StrictJavaDepsPlugin;
+import com.google.devtools.build.java.turbine.javac.JavacTurbineCompileRequest.Prune;
 
 import com.sun.tools.javac.comp.AttrContext;
 import com.sun.tools.javac.comp.CompileStates.CompileState;
@@ -38,15 +39,21 @@
 class JavacTurbineJavaCompiler extends JavaCompiler implements AutoCloseable {
 
   @Nullable private final StrictJavaDepsPlugin strictJavaDeps;
+  private final boolean prune;
 
-  public JavacTurbineJavaCompiler(Context context, @Nullable StrictJavaDepsPlugin strictJavaDeps) {
+  public JavacTurbineJavaCompiler(
+      Context context, @Nullable StrictJavaDepsPlugin strictJavaDeps, Prune prune) {
     super(context);
     this.strictJavaDeps = strictJavaDeps;
+    this.prune = prune == Prune.YES;
   }
 
   @Override
   protected JCCompilationUnit parse(JavaFileObject javaFileObject, CharSequence charSequence) {
     JCCompilationUnit result = super.parse(javaFileObject, charSequence);
+    if (!prune) {
+      return result;
+    }
     TreePruner.prune(result);
     return result;
   }
@@ -65,6 +72,10 @@ public Env<AttrContext> attribute(Env<AttrContext> env) {
 
   @Override
   protected void flow(Env<AttrContext> env, Queue<Env<AttrContext>> results) {
+    if (!prune) {
+      super.flow(env, results);
+      return;
+    }
     // skip FLOW (as if -relax was enabled, except -relax is broken for JDK >= 8)
     if (!compileStates.isDone(env, CompileState.FLOW)) {
       compileStates.put(env, CompileState.FLOW);
@@ -83,13 +94,14 @@ public void close() {
    * Override the default {@link JavaCompiler} implementation with {@link JavacTurbineJavaCompiler}
    * for the given compilation context.
    */
-  public static void preRegister(Context context, @Nullable final StrictJavaDepsPlugin sjd) {
+  public static void preRegister(
+      Context context, @Nullable final StrictJavaDepsPlugin sjd, final Prune prune) {
     context.put(
         compilerKey,
         new Context.Factory<JavaCompiler>() {
           @Override
           public JavaCompiler make(Context c) {
-            return new JavacTurbineJavaCompiler(c, sjd);
+            return new JavacTurbineJavaCompiler(c, sjd, prune);
           }
         });
   }
diff --git a/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/BUILD b/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/BUILD
index 04419b0ad56d1a..4132bba9df711b 100644
--- a/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/BUILD
+++ b/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/BUILD
@@ -1,6 +1,13 @@
 java_test(
     name = "JavacTurbineTest",
     srcs = ["JavacTurbineTest.java"],
+    data = [
+        "//third_party/java/jdk/langtools:javac_jar",
+    ],
+    jvm_flags = [
+        # Simulates how Bazel invokes turbine
+        "-Xbootclasspath/p:$(location //third_party/java/jdk/langtools:javac_jar)",
+    ],
     tags = ["jdk8"],
     deps = [
         "//src/java_tools/buildjar/java/com/google/devtools/build/java/turbine:turbine_options",
diff --git a/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/JavacTurbineTest.java b/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/JavacTurbineTest.java
index 2fdc22d9d63214..234f5d0865332e 100644
--- a/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/JavacTurbineTest.java
+++ b/src/java_tools/buildjar/javatests/com/google/devtools/build/java/turbine/javac/JavacTurbineTest.java
@@ -15,6 +15,7 @@
 package com.google.devtools.build.java.turbine.javac;
 
 import static com.google.common.truth.Truth.assertThat;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.base.Function;
 import com.google.common.base.Joiner;
@@ -28,7 +29,12 @@
 import com.google.devtools.build.lib.view.proto.Deps;
 import com.google.devtools.build.lib.view.proto.Deps.Dependency;
 
+import com.sun.source.tree.LiteralTree;
 import com.sun.source.util.JavacTask;
+import com.sun.source.util.TaskEvent;
+import com.sun.source.util.TaskEvent.Kind;
+import com.sun.source.util.TaskListener;
+import com.sun.source.util.TreeScanner;
 import com.sun.tools.javac.api.ClientCodeWrapper.Trusted;
 import com.sun.tools.javac.api.JavacTool;
 import com.sun.tools.javac.file.JavacFileManager;
@@ -52,7 +58,6 @@
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.net.URI;
-import java.nio.charset.StandardCharsets;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -63,6 +68,7 @@
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -71,6 +77,7 @@
 import java.util.jar.JarOutputStream;
 
 import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.ProcessingEnvironment;
 import javax.annotation.processing.RoundEnvironment;
 import javax.annotation.processing.SupportedAnnotationTypes;
 import javax.lang.model.SourceVersion;
@@ -120,7 +127,7 @@ public void setUp() throws IOException {
   private void addSourceLines(String path, String... lines) throws IOException {
     Path source = sourcedir.resolve(path);
     sources.add(source);
-    Files.write(source, Arrays.asList(lines), StandardCharsets.UTF_8);
+    Files.write(source, Arrays.asList(lines), UTF_8);
   }
 
   void compile() throws IOException {
@@ -231,7 +238,7 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
       try {
         JavaFileObject sourceFile = processingEnv.getFiler().createSourceFile("Generated", element);
         try (OutputStream os = sourceFile.openOutputStream()) {
-          os.write("public class Generated {}".getBytes(StandardCharsets.UTF_8));
+          os.write("public class Generated {}".getBytes(UTF_8));
         }
       } catch (IOException e) {
         throw new IOError(e);
@@ -242,7 +249,7 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
                 .getFiler()
                 .createResource(StandardLocation.CLASS_OUTPUT, "com.foo", "hello.txt", element);
         try (OutputStream os = file.openOutputStream()) {
-          os.write("hello".getBytes(StandardCharsets.UTF_8));
+          os.write("hello".getBytes(UTF_8));
         }
       } catch (IOException e) {
         throw new IOError(e);
@@ -455,7 +462,7 @@ private void compileLib(
       Path jar, Iterable<Path> classpath, Iterable<? extends JavaFileObject> units)
       throws IOException {
     final Path outdir = temp.newFolder().toPath();
-    JavacFileManager fm = new JavacFileManager(new Context(), false, StandardCharsets.UTF_8);
+    JavacFileManager fm = new JavacFileManager(new Context(), false, UTF_8);
     fm.setLocationFromPaths(StandardLocation.CLASS_OUTPUT, Collections.singleton(outdir));
     fm.setLocationFromPaths(StandardLocation.CLASS_PATH, classpath);
     List<String> options = Arrays.asList("-d", outdir.toString());
@@ -795,10 +802,9 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
       try {
         JavaFileObject sourceFile = processingEnv.getFiler().createSourceFile("Generated", element);
         try (OutputStream os = sourceFile.openOutputStream()) {
-          os.write(
-              "class Generated { public static String x = \"".getBytes(StandardCharsets.UTF_8));
+          os.write("class Generated { public static String x = \"".getBytes(UTF_8));
           os.write(0xc2); // write an unpaired surrogate
-          os.write("\";}}".getBytes(StandardCharsets.UTF_8));
+          os.write("\";}}".getBytes(UTF_8));
         }
       } catch (IOException e) {
         throw new IOError(e);
@@ -936,7 +942,7 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
                 .getFiler()
                 .createResource(StandardLocation.CLASS_OUTPUT, "", "result.txt");
         try (OutputStream os = fileObject.openOutputStream()) {
-          os.write(message.getBytes(StandardCharsets.UTF_8));
+          os.write(message.getBytes(UTF_8));
         }
       } catch (IOException e) {
         throw new IOError(e);
@@ -951,15 +957,7 @@ public void maskProcessorClasspath() throws Exception {
     addSourceLines("Hello.java", "@MyAnnotation class Hello {}");
 
     // create a jar containing only HostClasspathProcessor
-    Path processorJar = temp.newFile("libprocessor.jar").toPath();
-    try (OutputStream os = Files.newOutputStream(processorJar);
-        JarOutputStream jos = new JarOutputStream(os)) {
-      String classFileName = HostClasspathProcessor.class.getName().replace('.', '/') + ".class";
-      jos.putNextEntry(new JarEntry(classFileName));
-      try (InputStream is = getClass().getClassLoader().getResourceAsStream(classFileName)) {
-        ByteStreams.copy(is, jos);
-      }
-    }
+    Path processorJar = createClassJar("libprocessor.jar", HostClasspathProcessor.class);
 
     optionsBuilder.addProcessors(ImmutableList.of(HostClasspathProcessor.class.getName()));
     optionsBuilder.addProcessorPathEntries(ImmutableList.of(processorJar.toString()));
@@ -970,27 +968,42 @@ public void maskProcessorClasspath() throws Exception {
     Map<String, byte[]> outputs = collectOutputs();
     assertThat(outputs.keySet()).contains("result.txt");
 
-    String text = new String(outputs.get("result.txt"), StandardCharsets.UTF_8);
+    String text = new String(outputs.get("result.txt"), UTF_8);
     assertThat(text)
         .contains(
             "java.lang.NoClassDefFoundError:"
                 + " com/google/devtools/build/java/turbine/javac/JavacTurbine");
   }
 
+  private Path createClassJar(String jarName, Class<?>... classes) throws IOException {
+    Path jarPath = temp.newFile(jarName).toPath();
+    try (OutputStream os = Files.newOutputStream(jarPath);
+        JarOutputStream jos = new JarOutputStream(os)) {
+      for (Class<?> clazz : classes) {
+        String classFileName = clazz.getName().replace('.', '/') + ".class";
+        jos.putNextEntry(new JarEntry(classFileName));
+        try (InputStream is = getClass().getClassLoader().getResourceAsStream(classFileName)) {
+          ByteStreams.copy(is, jos);
+        }
+      }
+    }
+    return jarPath;
+  }
+
   @Test
   public void overlappingSourceJars() throws Exception {
     Path sourceJar1 = temp.newFile("srcs1.jar").toPath();
     try (OutputStream os = Files.newOutputStream(sourceJar1);
         JarOutputStream jos = new JarOutputStream(os)) {
       jos.putNextEntry(new JarEntry("Hello.java"));
-      jos.write("public class Hello {}".getBytes(StandardCharsets.UTF_8));
+      jos.write("public class Hello {}".getBytes(UTF_8));
     }
 
     Path sourceJar2 = temp.newFile("srcs2.jar").toPath();
     try (OutputStream os = Files.newOutputStream(sourceJar2);
         JarOutputStream jos = new JarOutputStream(os)) {
       jos.putNextEntry(new JarEntry("Hello.java"));
-      jos.write("public class Hello {}".getBytes(StandardCharsets.UTF_8));
+      jos.write("public class Hello {}".getBytes(UTF_8));
     }
 
     optionsBuilder.setSourceJars(ImmutableList.of(sourceJar2.toString(), sourceJar1.toString()));
@@ -1090,4 +1103,110 @@ public void emptySources() throws Exception {
     Map<String, byte[]> outputs = collectOutputs();
     assertThat(outputs.keySet()).containsExactly("dummy");
   }
+
+  /** An annotation processor that violates the contract. */
+  @SupportedAnnotationTypes("*")
+  public static class MisguidedAnnotationProcessor extends AbstractProcessor {
+
+    public final class Scanner extends TreeScanner<Void, Void> {
+      @Override
+      public Void visitLiteral(LiteralTree tree, Void unused) {
+        values.add(tree.getValue());
+        return null;
+      }
+    }
+
+    public final class Listener implements TaskListener {
+
+      public final ProcessingEnvironment processingEnv;
+
+      Listener(ProcessingEnvironment processingEnv) {
+        this.processingEnv = processingEnv;
+      }
+
+      @Override
+      public void started(TaskEvent e) {}
+
+      @Override
+      public void finished(TaskEvent e) {
+        if (e.getKind() == Kind.ANALYZE) {
+          e.getCompilationUnit().accept(new Scanner(), null);
+        } else if (e.getKind() == Kind.GENERATE) {
+          try {
+            FileObject file =
+                processingEnv
+                    .getFiler()
+                    .createResource(
+                        StandardLocation.CLASS_OUTPUT, "", "output.txt", e.getTypeElement());
+            try (OutputStream os = file.openOutputStream()) {
+              os.write(values.toString().getBytes(UTF_8));
+            }
+          } catch (IOException exception) {
+            throw new IOError(exception);
+          }
+        }
+      }
+    }
+
+    public final Set<Object> values = new LinkedHashSet<>();
+
+    @Override
+    public SourceVersion getSupportedSourceVersion() {
+      return SourceVersion.latest();
+    }
+
+    @Override
+    public synchronized void init(final ProcessingEnvironment processingEnv) {
+      JavacTask.instance(processingEnv).addTaskListener(new Listener(processingEnv));
+    }
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+      return false;
+    }
+  }
+
+  void setupMisguidedProcessor() throws Exception {
+    addSourceLines(
+        "Hello.java",
+        "@Deprecated class Hello {",
+        "  int x = 42;",
+        "  String s = \"hello\";",
+        "  double y = 42.1;",
+        "}");
+
+    Path processorJar =
+        createClassJar(
+            "libprocessor.jar",
+            MisguidedAnnotationProcessor.class,
+            MisguidedAnnotationProcessor.Listener.class,
+            MisguidedAnnotationProcessor.Scanner.class);
+
+    optionsBuilder.addProcessors(ImmutableList.of(MisguidedAnnotationProcessor.class.getName()));
+    optionsBuilder.addProcessorPathEntries(ImmutableList.of(processorJar.toString()));
+  }
+
+  @Test
+  public void misguidedProcessor_pruning() throws Exception {
+    setupMisguidedProcessor();
+    compile();
+    Map<String, byte[]> outputs = collectOutputs();
+
+    assertThat(outputs.keySet()).containsExactly("Hello.class", "output.txt");
+    String output = new String(outputs.get("output.txt"), UTF_8);
+    assertThat(output).isEqualTo("[]");
+  }
+
+  @Test
+  public void misguidedProcessor() throws Exception {
+    setupMisguidedProcessor();
+    optionsBuilder.addBlacklistedProcessors(
+        ImmutableList.of(MisguidedAnnotationProcessor.class.getName()));
+    compile();
+    Map<String, byte[]> outputs = collectOutputs();
+
+    assertThat(outputs.keySet()).containsExactly("Hello.class", "output.txt");
+    String output = new String(outputs.get("output.txt"), UTF_8);
+    assertThat(output).isEqualTo("[42, hello, 42.1]");
+  }
 }