diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 06513ac..5f1bf47 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -308,7 +308,7 @@
 
     @Option(
         name = "incompatible_merge_genfiles_directory",
-        defaultValue = "false",
+        defaultValue = "true",
         documentationCategory = OptionDocumentationCategory.OUTPUT_PARAMETERS,
         effectTags = {OptionEffectTag.AFFECTS_OUTPUTS},
         metadataTags = {
@@ -1417,6 +1417,10 @@
 
   /** Returns the genfiles directory for this build configuration. */
   public ArtifactRoot getGenfilesDirectory() {
+    if (mergeGenfilesDirectory) {
+      return getBinDirectory();
+    }
+
     return getGenfilesDirectory(RepositoryName.MAIN);
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/query2/ActionGraphProtoOutputFormatterCallbackTest.java b/src/test/java/com/google/devtools/build/lib/query2/ActionGraphProtoOutputFormatterCallbackTest.java
index b7b0d2e..4867a3a 100644
--- a/src/test/java/com/google/devtools/build/lib/query2/ActionGraphProtoOutputFormatterCallbackTest.java
+++ b/src/test/java/com/google/devtools/build/lib/query2/ActionGraphProtoOutputFormatterCallbackTest.java
@@ -199,7 +199,7 @@
         "genrule(name='wrong_outputs', srcs=['matching_in'], outs=['wrong_out'],",
         "        cmd='cat $(SRCS) > $(OUTS)')");
 
-    String outputs = ".*/genfiles/test/foo_matching_out";
+    String outputs = ".*/bin/test/foo_matching_out";
     AqueryActionFilter actionFilters = constructActionFilter(ImmutableMap.of("outputs", outputs));
 
     ActionGraphContainer actionGraphContainer =
@@ -921,10 +921,7 @@
 
   private void assertMatchingOnlyActionFromFoo(ActionGraphContainer actionGraphContainer) {
     assertMatchingOnlyAction(
-        actionGraphContainer,
-        "Genrule",
-        "test/foo_matching_in.java",
-        "/genfiles/test/foo_matching_out");
+        actionGraphContainer, "Genrule", "test/foo_matching_in.java", "/bin/test/foo_matching_out");
   }
 
   private void assertMatchingOnlyAction(
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
index 65fb24c..8994736 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcCommonTest.java
@@ -496,7 +496,7 @@
   @Test
   public void testUseIsystemForIncludes() throws Exception {
     // Tests the effect of --use_isystem_for_includes.
-
+    useConfiguration("--incompatible_merge_genfiles_directory=false");
     scratch.file(
         "no_includes/BUILD",
         "cc_library(name = 'no_includes',",
diff --git a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
index 102d12e..a4a2823 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/cpp/CcLibraryConfiguredTargetTest.java
@@ -1118,6 +1118,7 @@
 
   @Test
   public void testIncludePathOrder() throws Exception {
+    useConfiguration("--incompatible_merge_genfiles_directory=false");
     scratch.file("foo/BUILD",
         "cc_library(",
         "    name = 'bar',",
diff --git a/src/test/shell/bazel/bazel_rules_test.sh b/src/test/shell/bazel/bazel_rules_test.sh
index 0676d27..a129030 100755
--- a/src/test/shell/bazel/bazel_rules_test.sh
+++ b/src/test/shell/bazel/bazel_rules_test.sh
@@ -309,18 +309,18 @@
 
     # Test that Bazel respects the client environment's TMP.
     # new_tmpdir is based on $TEST_TMPDIR which is not Unix-style -- convert it.
-    assert_contains "TMP=$(cygpath -u "${new_tmpdir}")" bazel-genfiles/pkg/test.out
+    assert_contains "TMP=$(cygpath -u "${new_tmpdir}")" bazel-bin/pkg/test.out
   else
     PATH="/random/path:$PATH" TMPDIR="${new_tmpdir}" \
       bazel build //pkg:test --spawn_strategy=standalone --action_env=PATH \
       &> $TEST_log || fail "Failed to build //pkg:test"
 
     # Test that Bazel respects the client environment's TMPDIR.
-    assert_contains "TMPDIR=${new_tmpdir}" bazel-genfiles/pkg/test.out
+    assert_contains "TMPDIR=${new_tmpdir}" bazel-bin/pkg/test.out
   fi
 
   # Test that Bazel passed through the PATH from --action_env.
-  assert_contains "PATH=/random/path" bazel-genfiles/pkg/test.out
+  assert_contains "PATH=/random/path" bazel-bin/pkg/test.out
 }
 
 function test_genrule_remote() {
@@ -374,8 +374,8 @@
 EOF
 
   bazel build @r//package:hi >$TEST_log 2>&1 || fail "Should build"
-  expect_log "bazel-.*genfiles/external/r/package/a/b"
-  expect_log "bazel-.*genfiles/external/r/package/c/d"
+  expect_log "bazel-.*bin/external/r/package/a/b"
+  expect_log "bazel-.*bin/external/r/package/c/d"
 }
 
 function test_genrule_toolchain_dependency {
@@ -389,7 +389,7 @@
 )
 EOF
   bazel build //t:toolchain_check >$TEST_log 2>&1 || fail "Should build"
-  expect_log "bazel-.*genfiles/t/version"
+  expect_log "bazel-.*bin/t/version"
   expect_not_log "ls: cannot access"
 }