diff --git a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
index ec29773f021083..74c11be759af58 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/DependencyResolver.java
@@ -679,10 +679,8 @@ private <T> void resolveAttribute(
       return;
     }
 
-    Label ruleLabel = rule.getLabel();
     type.visitLabels(
-        (depLabel, ctx) ->
-            outgoingLabels.put(dependencyKind, ruleLabel.resolveRepositoryRelative(depLabel)),
+        (depLabel, ctx) -> outgoingLabels.put(dependencyKind, depLabel),
         attributeValue,
         /*context=*/ null);
   }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java b/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
index 58dd68d9221048..a245cb361c1e88 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/OutputDirectories.java
@@ -256,7 +256,7 @@ private ArtifactRoot buildDerivedRoot(
     // instead. However, it requires individually symlinking the top-level elements of external
     // repositories, which is blocked by a Windows symlink issue #8704.
     RootType rootType;
-    if (repository.isMain() || repository.isDefault()) {
+    if (repository.isMain()) {
       rootType = isMiddleman ? RootType.SiblingMainMiddleman : RootType.SiblingMainOutput;
     } else {
       rootType = isMiddleman ? RootType.SiblingExternalMiddleman : RootType.SiblingExternalOutput;
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
index b98c164704e9da..14ce51ea507038 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleClassFunctions.java
@@ -130,7 +130,6 @@ public Label load(String from) throws Exception {
                   try {
                     return Label.parseAbsolute(
                         from,
-                        /* defaultToMain=*/ false,
                         /* repositoryMapping= */ ImmutableMap.of());
                   } catch (LabelSyntaxException e) {
                     throw new Exception(from);
diff --git a/src/main/java/com/google/devtools/build/lib/buildtool/SymlinkForest.java b/src/main/java/com/google/devtools/build/lib/buildtool/SymlinkForest.java
index f8ece0f13526de..9a70756ce107d2 100644
--- a/src/main/java/com/google/devtools/build/lib/buildtool/SymlinkForest.java
+++ b/src/main/java/com/google/devtools/build/lib/buildtool/SymlinkForest.java
@@ -364,7 +364,7 @@ public ImmutableList<Path> plantSymlinkForest() throws IOException, AbruptExitEx
         continue;
       }
       RepositoryName repository = pkgId.getRepository();
-      if (repository.isMain() || repository.isDefault()) {
+      if (repository.isMain()) {
         // Record main repo packages.
         packageRootsForMainRepo.put(entry.getKey(), entry.getValue());
 
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
index 21a2e040ddebf0..1acdae6fbc5ad3 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/BUILD
@@ -55,6 +55,7 @@ java_library(
     name = "cmdline-primitives",
     srcs = [
         "LabelConstants.java",
+        "LabelParser.java",
         "LabelSyntaxException.java",
         "PackageIdentifier.java",
         "RepositoryMapping.java",
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
index d5295952c6bada..d592862f65e937 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/Label.java
@@ -13,20 +13,20 @@
 // limitations under the License.
 package com.google.devtools.build.lib.cmdline;
 
+import static com.google.devtools.build.lib.cmdline.LabelParser.validateAndProcessTargetName;
+
 import com.google.common.base.Preconditions;
 import com.google.common.collect.ComparisonChain;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Interner;
 import com.google.devtools.build.docgen.annot.DocCategory;
 import com.google.devtools.build.lib.actions.CommandLineItem;
-import com.google.devtools.build.lib.cmdline.LabelValidator.BadLabelException;
+import com.google.devtools.build.lib.cmdline.LabelParser.Parts;
 import com.google.devtools.build.lib.concurrent.BlazeInterners;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
 import com.google.devtools.build.lib.packages.semantics.BuildLanguageOptions;
 import com.google.devtools.build.lib.skyframe.serialization.autocodec.AutoCodec;
-import com.google.devtools.build.lib.util.StringUtilities;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.skyframe.SkyFunctionName;
 import com.google.devtools.build.skyframe.SkyKey;
@@ -61,58 +61,74 @@ public final class Label implements Comparable<Label>, StarlarkValue, SkyKey, Co
   private static final String PKG_VISIBILITY_NAME = "__pkg__";
   private static final String SUBPACKAGES_VISIBILITY_NAME = "__subpackages__";
 
-  /**
-   * Package names that aren't made relative to the current repository because they mean special
-   * things to Bazel.
-   */
-  private static final ImmutableSet<PathFragment> ABSOLUTE_PACKAGE_NAMES =
-      ImmutableSet.of(
-          // Used for select
-          PathFragment.create("conditions"),
-          // Visibility is labels aren't actually targets
-          PathFragment.create("visibility"),
-          // There is only one //external package
-          LabelConstants.EXTERNAL_PACKAGE_NAME);
-
   public static final SkyFunctionName TRANSITIVE_TRAVERSAL =
       SkyFunctionName.createHermetic("TRANSITIVE_TRAVERSAL");
 
   private static final Interner<Label> LABEL_INTERNER = BlazeInterners.newWeakInterner();
 
+  // TODO(b/200024947): Make this public.
   /**
-   * Factory for Labels from absolute string form. e.g.
-   *
-   * <pre>
-   * //foo/bar
-   * //foo/bar:quux
-   * {@literal @}foo
-   * {@literal @}foo//bar
-   * {@literal @}foo//bar:baz
-   * </pre>
-   *
-   * <p>Treats labels in the default repository as being in the main repository instead.
-   *
-   * <p>Labels that begin with a repository name may have the repository name remapped to a
-   * different name if it appears in {@code repositoryMapping}. This happens if the current
-   * repository being evaluated is external to the main repository and the main repository set the
-   * {@code repo_mapping} attribute when declaring this repository.
-   *
-   * @param absName label-like string to be parsed
-   * @param repositoryMapping map of repository names from the local name found in the current
-   *     repository to the global name declared in the main repository
+   * Parses a raw label string that contains the canonical form of a label. It must be of the form
+   * {@code [@repo]//foo/bar[:quux]}. If the {@code @repo} part is present, it must be a canonical
+   * repo name, otherwise the label will be assumed to be in the main repo.
    */
-  public static Label parseAbsolute(String absName, RepositoryMapping repositoryMapping)
+  private static Label parseCanonical(String raw) throws LabelSyntaxException {
+    Parts parts = Parts.parse(raw);
+    parts.checkPkgIsAbsolute();
+    RepositoryName repoName =
+        parts.repo == null
+            ? RepositoryName.MAIN
+            : RepositoryName.createFromValidStrippedName(parts.repo);
+    return createUnvalidated(
+        PackageIdentifier.create(repoName, PathFragment.create(parts.pkg)), parts.target);
+  }
+
+  // TODO(b/200024947): Make this public.
+  /**
+   * Parses a raw label string within the context of a current repo. It must be of the form {@code
+   * [@repo]//foo/bar[:quux]}. If the {@code @repo} part is present, it will undergo {@code
+   * repoMapping}, otherwise the label will be assumed to be in {@code currentRepo}.
+   */
+  private static Label parseWithRepoContext(
+      String raw, RepositoryName currentRepo, RepositoryMapping repoMapping)
       throws LabelSyntaxException {
-    return parseAbsolute(absName, /*defaultToMain=*/ true, repositoryMapping);
-  }
-
-  public static Label parseAbsolute(
-      String absName, ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
+    Parts parts = Parts.parse(raw);
+    parts.checkPkgIsAbsolute();
+    // TODO(b/200024947): Make repo mapping take a string and return a RepositoryName.
+    RepositoryName repoName =
+        parts.repo == null
+            ? currentRepo
+            : repoMapping.get(RepositoryName.createFromValidStrippedName(parts.repo));
+    return createUnvalidated(
+        PackageIdentifier.create(repoName, PathFragment.create(parts.pkg)), parts.target);
+  }
+
+  // TODO(b/200024947): Make this public.
+  /**
+   * Parses a raw label string within the context of a current package. It can be of a
+   * package-relative form ({@code :quux}). Otherwise, it must be of the form {@code
+   * [@repo]//foo/bar[:quux]}. If the {@code @repo} part is present, it will undergo {@code
+   * repoMapping}, otherwise the label will be assumed to be in the repo of {@code
+   * packageIdentifier}.
+   */
+  private static Label parseWithPackageContext(
+      String raw, PackageIdentifier packageIdentifier, RepositoryMapping repoMapping)
       throws LabelSyntaxException {
-    return parseAbsolute(
-        absName,
-        /*defaultToMain=*/ true,
-        RepositoryMapping.createAllowingFallback(repositoryMapping));
+    Parts parts = Parts.parse(raw);
+    // pkg is either absolute or empty
+    if (!parts.pkg.isEmpty()) {
+      parts.checkPkgIsAbsolute();
+    }
+    // TODO(b/200024947): Make repo mapping take a string and return a RepositoryName.
+    RepositoryName repoName =
+        parts.repo == null
+            ? packageIdentifier.getRepository()
+            : repoMapping.get(RepositoryName.createFromValidStrippedName(parts.repo));
+    PathFragment pkgFragment =
+        parts.pkgIsAbsolute
+            ? PathFragment.create(parts.pkg)
+            : packageIdentifier.getPackageFragment();
+    return createUnvalidated(PackageIdentifier.create(repoName, pkgFragment), parts.target);
   }
 
   /**
@@ -126,56 +142,27 @@ public static Label parseAbsolute(
    * {@literal @}foo//bar:baz
    * </pre>
    *
-   * <p>Labels that begin with a repository name may have the repository name remapped to a
-   * different name if it appears in {@code repositoryMapping}. This happens if the current
-   * repository being evaluated is external to the main repository and the main repository set the
-   * {@code repo_mapping} attribute when declaring this repository.
+   * <p>Labels that don't begin with a repository name are considered to be in the main repository,
+   * so for instance {@code //foo/bar} will turn into {@code @//foo/bar}.
+   *
+   * <p>Labels that begin with a repository name will undergo {@code repositoryMapping}.
    *
    * @param absName label-like string to be parsed
-   * @param defaultToMain Treat labels in the default repository as being in the main one instead.
    * @param repositoryMapping map of repository names from the local name found in the current
    *     repository to the global name declared in the main repository
    */
-  public static Label parseAbsolute(
-      String absName, boolean defaultToMain, RepositoryMapping repositoryMapping)
+  // TODO(b/200024947): Remove this.
+  public static Label parseAbsolute(String absName, RepositoryMapping repositoryMapping)
       throws LabelSyntaxException {
     Preconditions.checkNotNull(repositoryMapping);
-    String repo = defaultToMain ? "@" : RepositoryName.DEFAULT_REPOSITORY;
-    int packageStartPos = absName.indexOf("//");
-    if (packageStartPos > 0) {
-      repo = absName.substring(0, packageStartPos);
-      absName = absName.substring(packageStartPos);
-    } else if (absName.startsWith("@")) {
-      repo = absName;
-      absName = "//:" + absName.substring(1);
-    }
-    String error = RepositoryName.validate(repo);
-    if (error != null) {
-      throw new LabelSyntaxException(
-          "invalid repository name '" + StringUtilities.sanitizeControlChars(repo) + "': " + error);
-    }
-    try {
-      LabelValidator.PackageAndTarget labelParts = LabelValidator.parseAbsoluteLabel(absName);
-      PackageIdentifier pkgId =
-          validatePackageName(
-              labelParts.getPackageName(), labelParts.getTargetName(), repo, repositoryMapping);
-      PathFragment packageFragment = pkgId.getPackageFragment();
-      if (repo.isEmpty() && ABSOLUTE_PACKAGE_NAMES.contains(packageFragment)) {
-        pkgId = PackageIdentifier.create(RepositoryName.MAIN, packageFragment);
-      }
-      return create(pkgId, labelParts.getTargetName());
-    } catch (BadLabelException e) {
-      throw new LabelSyntaxException(e.getMessage());
-    }
+    return parseWithRepoContext(absName, RepositoryName.MAIN, repositoryMapping);
   }
 
+  // TODO(b/200024947): Remove this.
   public static Label parseAbsolute(
-      String absName,
-      boolean defaultToMain,
-      ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
+      String absName, ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
       throws LabelSyntaxException {
-    return parseAbsolute(
-        absName, defaultToMain, RepositoryMapping.createAllowingFallback(repositoryMapping));
+    return parseAbsolute(absName, RepositoryMapping.createAllowingFallback(repositoryMapping));
   }
 
   /**
@@ -185,20 +172,15 @@ public static Label parseAbsolute(
    *
    * <p>Do not use this when the argument is not hard-wired.
    */
-  @Deprecated
-  // TODO(b/110698008): create parseAbsoluteUnchecked that passes repositoryMapping
-  public static Label parseAbsoluteUnchecked(String absName, boolean defaultToMain) {
+  // TODO(b/200024947): Remove this.
+  public static Label parseAbsoluteUnchecked(String absName) {
     try {
-      return parseAbsolute(absName, defaultToMain, /* repositoryMapping= */ ImmutableMap.of());
+      return parseCanonical(absName);
     } catch (LabelSyntaxException e) {
       throw new IllegalArgumentException(e);
     }
   }
 
-  public static Label parseAbsoluteUnchecked(String absName) {
-    return parseAbsoluteUnchecked(absName, true);
-  }
-
   /**
    * Factory for Labels from separate components.
    *
@@ -208,17 +190,23 @@ public static Label parseAbsoluteUnchecked(String absName) {
    *     LabelValidator#validateTargetName}.
    * @throws LabelSyntaxException if either of the arguments was invalid.
    */
+  // TODO(b/200024947): Remove this...?
   public static Label create(String packageName, String targetName) throws LabelSyntaxException {
-    return create(validatePackageName(packageName, targetName), targetName);
+    return createUnvalidated(
+        PackageIdentifier.parse(packageName),
+        validateAndProcessTargetName(packageName, targetName));
   }
 
   /**
    * Similar factory to above, but takes a package identifier to allow external repository labels to
    * be created.
    */
+  // TODO(b/200024947): Remove this...?
   public static Label create(PackageIdentifier packageId, String targetName)
       throws LabelSyntaxException {
-    return createUnvalidated(packageId, validateTargetName(packageId, targetName));
+    return createUnvalidated(
+        packageId,
+        validateAndProcessTargetName(packageId.getPackageFragment().getPathString(), targetName));
   }
 
   /**
@@ -239,14 +227,15 @@ public static Label createUnvalidated(PackageIdentifier packageIdentifier, Strin
   }
 
   /**
-   * Resolves a relative label using a workspace-relative path to the current working directory. The
-   * method handles these cases:
+   * Parses and resolves a label string relative to the given workspace-relative directory.
    *
    * <ul>
-   *   <li>The label is absolute.
-   *   <li>The label starts with a colon.
-   *   <li>The label consists of a relative path, a colon, and a local part.
-   *   <li>The label consists only of a local part.
+   *   <li>If the input is an absolute label, it is parsed as normal.
+   *   <li>If the input starts with a colon or does not contain a colon, the package path is taken
+   *       to be the working directory, and the part after the leading colon (if present) is taken
+   *       to be the target.
+   *   <li>If the input has a non-empty part before a colon, it is appended to the working directory
+   *       to form the package path, and the part after the colon is taken as the target.
    * </ul>
    *
    * <p>Note that this method does not support any of the special syntactic constructs otherwise
@@ -258,70 +247,22 @@ public static Label createUnvalidated(PackageIdentifier packageIdentifier, Strin
    *
    * @throws LabelSyntaxException if the resulting label is not valid
    */
-  public static Label parseCommandLineLabel(String label, PathFragment workspaceRelativePath)
+  public static Label parseCommandLineLabel(String raw, PathFragment workspaceRelativePath)
       throws LabelSyntaxException {
     Preconditions.checkArgument(!workspaceRelativePath.isAbsolute());
-    if (LabelValidator.isAbsolute(label)) {
-      return parseAbsolute(label, RepositoryMapping.ALWAYS_FALLBACK);
-    }
-    int index = label.indexOf(':');
-    if (index < 0) {
-      index = 0;
-      label = ":" + label;
-    }
-    PathFragment path = workspaceRelativePath.getRelative(label.substring(0, index));
-    // Use the String, String constructor, to make sure that the package name goes through the
-    // validity check.
-    return create(path.getPathString(), label.substring(index + 1));
-  }
-
-  /**
-   * Validates the given target name and returns a normalized name if it is valid. Otherwise it
-   * throws a SyntaxException.
-   */
-  private static String validateTargetName(PackageIdentifier packageIdentifier, String name)
-      throws LabelSyntaxException {
-    String error = LabelValidator.validateTargetName(name);
-    if (error != null) {
-      error = "invalid target name '" + StringUtilities.sanitizeControlChars(name) + "': " + error;
-      if (packageIdentifier.getPackageFragment().getPathString().endsWith("/" + name)) {
-        error += " (perhaps you meant \":" + name + "\"?)";
-      }
-      throw new LabelSyntaxException(error);
-    }
-
-    // TODO(bazel-team): This should be an error, but we can't make it one for legacy reasons.
-    if (name.endsWith("/.")) {
-      name = name.substring(0, name.length() - 2);
-    }
-    return name;
-  }
-
-  private static PackageIdentifier validatePackageName(String packageIdentifier, String name)
-      throws LabelSyntaxException {
-    return validatePackageName(
-        packageIdentifier, name, /* repo= */ null, /* repositoryMapping= */ null);
-  }
-
-  /**
-   * Validates the given package name and returns a canonical {@link PackageIdentifier} instance if
-   * it is valid. Otherwise it throws a SyntaxException.
-   */
-  private static PackageIdentifier validatePackageName(
-      String packageIdentifier, String name, String repo, RepositoryMapping repositoryMapping)
-      throws LabelSyntaxException {
-    try {
-      return PackageIdentifier.parse(packageIdentifier, repo, repositoryMapping);
-    } catch (LabelSyntaxException e) {
-      String error = "invalid package name '" + packageIdentifier + "': " + e.getMessage();
-      // This check is just for a more helpful error message
-      // i.e. valid target name, invalid package name, colon-free label form
-      // used => probably they meant "//foo:bar.c" not "//foo/bar.c".
-      if (packageIdentifier.endsWith("/" + name)) {
-        error += " (perhaps you meant \":" + name + "\"?)";
-      }
-      throw new LabelSyntaxException(error);
+    Parts parts = Parts.parse(raw);
+    PathFragment pathFragment;
+    if (parts.repo == null && !parts.pkgIsAbsolute) {
+      pathFragment = workspaceRelativePath.getRelative(parts.pkg);
+    } else {
+      pathFragment = PathFragment.create(parts.pkg);
     }
+    // TODO(b/200024947): This method will eventually need to take a repo mapping too.
+    RepositoryName repoName =
+        parts.repo == null
+            ? RepositoryName.MAIN
+            : RepositoryName.createFromValidStrippedName(parts.repo);
+    return create(PackageIdentifier.create(repoName, pathFragment), parts.target);
   }
 
   /** The name and repository of the package. */
@@ -565,27 +506,17 @@ public interface HasRepoMapping {
    * @param repositoryMapping the map of local repository names in external repository to global
    *     repository names in main repo; can be empty, but not null
    */
+  // TODO(b/200024947): Remove this.
   public Label getRelativeWithRemapping(String relName, RepositoryMapping repositoryMapping)
       throws LabelSyntaxException {
     Preconditions.checkNotNull(repositoryMapping);
     if (relName.isEmpty()) {
       throw new LabelSyntaxException("empty package-relative label");
     }
-
-    if (LabelValidator.isAbsolute(relName)) {
-      // If this label is in the main repository, default the new label to the main repo as well to
-      // save resolveRepositoryRelative some work.
-      return resolveRepositoryRelative(
-          parseAbsolute(relName, /*defaultToMain=*/ getRepository().isMain(), repositoryMapping));
-    } else if (relName.equals(":")) {
-      throw new LabelSyntaxException("':' is not a valid package-relative label");
-    } else if (relName.charAt(0) == ':') {
-      return getLocalTargetLabel(relName.substring(1));
-    } else {
-      return getLocalTargetLabel(relName);
-    }
+    return parseWithPackageContext(relName, packageIdentifier, repositoryMapping);
   }
 
+  // TODO(b/200024947): Remove this.
   public Label getRelativeWithRemapping(
       String relName, ImmutableMap<RepositoryName, RepositoryName> repositoryMapping)
       throws LabelSyntaxException {
@@ -593,33 +524,6 @@ public Label getRelativeWithRemapping(
         relName, RepositoryMapping.createAllowingFallback(repositoryMapping));
   }
 
-  /**
-   * Resolves the repository of a label in the context of another label.
-   *
-   * <p>This is necessary so that dependency edges in remote repositories do not need to explicitly
-   * mention their repository name. Otherwise, referring to e.g. <code>//a:b</code> in a remote
-   * repository would point back to the main repository, which is usually not what is intended.
-   *
-   * <p>The return value will not be in the default repository.
-   */
-  public Label resolveRepositoryRelative(Label relative) {
-    if (packageIdentifier.getRepository().isDefault()
-        || !relative.packageIdentifier.getRepository().isDefault()) {
-      return relative;
-    }
-
-    try {
-      return create(
-          PackageIdentifier.create(
-              packageIdentifier.getRepository(), relative.getPackageFragment()),
-          relative.name);
-    } catch (LabelSyntaxException e) {
-      // We are creating the new label from an existing one which is guaranteed to be valid, so this
-      // can't happen.
-      throw new IllegalStateException(e);
-    }
-  }
-
   @Override
   public SkyFunctionName functionName() {
     return TRANSITIVE_TRAVERSAL;
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/LabelParser.java b/src/main/java/com/google/devtools/build/lib/cmdline/LabelParser.java
new file mode 100644
index 00000000000000..00612b91c91c5c
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/LabelParser.java
@@ -0,0 +1,195 @@
+// Copyright 2021 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.cmdline;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.util.StringUtilities;
+import com.google.errorprone.annotations.FormatMethod;
+import javax.annotation.Nullable;
+
+/** Utilities to help parse labels. */
+final class LabelParser {
+  /**
+   * Package names that aren't made relative to the current repository because they mean special
+   * things to Bazel.
+   */
+  private static final ImmutableSet<String> ABSOLUTE_PACKAGE_NAMES =
+      ImmutableSet.of(
+          // Used for select's `//conditions:default` label (not a target)
+          "conditions",
+          // Used for the public and private visibility labels (not targets)
+          "visibility",
+          // There is only one //external package
+          LabelConstants.EXTERNAL_PACKAGE_NAME.getPathString());
+
+  private LabelParser() {}
+
+  /**
+   * Contains the parsed elements of a label string. The parts are validated (they don't contain
+   * invalid characters). See {@link #parse} for valid label patterns.
+   */
+  static final class Parts {
+    /**
+     * The {@code @repo} part of the string (sans the {@literal @}); can be null if it doesn't have
+     * such a part.
+     */
+    @Nullable final String repo;
+    /** Whether the package part of the string is prefixed by double-slash. */
+    final boolean pkgIsAbsolute;
+    /** The package part of the string (sans double-slash, if any). */
+    final String pkg;
+    /** The target part of the string (sans colon). */
+    final String target;
+    /** The original unparsed raw string. */
+    final String raw;
+
+    private Parts(
+        @Nullable String repo, boolean pkgIsAbsolute, String pkg, String target, String raw) {
+      this.repo = repo;
+      this.pkgIsAbsolute = pkgIsAbsolute;
+      this.pkg = pkg;
+      this.target = target;
+      this.raw = raw;
+    }
+
+    private static Parts validateAndCreate(
+        @Nullable String repo, boolean pkgIsAbsolute, String pkg, String target, String raw)
+        throws LabelSyntaxException {
+      return new Parts(
+          validateAndProcessRepoName(repo, pkg),
+          pkgIsAbsolute,
+          validateAndProcessPackageName(pkg, target),
+          validateAndProcessTargetName(pkg, target),
+          raw);
+    }
+
+    /**
+     * Parses a raw label string into parts. The logic can be summarized by the following table:
+     *
+     * {@code
+     *  raw                 | repo   | pkgIsAbsolute | pkg       | target
+     * ---------------------+--------+---------------+-----------+-----------
+     *  foo/bar             | null   | false         | ""        | "foo/bar"
+     *  //foo/bar           | null   | true          | "foo/bar" | "bar"
+     *  @repo               | "repo" | true          | ""        | "repo"
+     *  @repo//foo/bar      | "repo" | true          | "foo/bar" | "bar"
+     *  :quux               | null   | false         | ""        | "quux"
+     *  foo/bar:quux        | null   | false         | "foo/bar" | "quux"
+     *  //foo/bar:quux      | null   | true          | "foo/bar" | "quux"
+     *  @repo//foo/bar:quux | "repo" | true          | "foo/bar" | "quux"
+     * }
+     */
+    static Parts parse(String rawLabel) throws LabelSyntaxException {
+      @Nullable final String repo;
+      final int startOfPackage;
+      final int doubleSlashIndex = rawLabel.indexOf("//");
+      final boolean pkgIsAbsolute;
+      if (rawLabel.startsWith("@")) {
+        if (doubleSlashIndex < 0) {
+          // Special case: the label "@foo" is synonymous with "@foo//:foo".
+          repo = rawLabel.substring(1);
+          return validateAndCreate(
+              repo, /*pkgIsAbsolute=*/ true, /*pkg=*/ "", /*target=*/ repo, rawLabel);
+        } else {
+          repo = rawLabel.substring(1, doubleSlashIndex);
+          startOfPackage = doubleSlashIndex + 2;
+          pkgIsAbsolute = true;
+        }
+      } else {
+        // If the label begins with '//', it's an absolute label. Otherwise, treat it as relative
+        // (the command-line kind).
+        pkgIsAbsolute = doubleSlashIndex == 0;
+        startOfPackage = doubleSlashIndex == 0 ? 2 : 0;
+        repo = null;
+      }
+
+      final String pkg;
+      final String target;
+      final int colonIndex = rawLabel.indexOf(':', startOfPackage);
+      if (colonIndex >= 0) {
+        pkg = rawLabel.substring(startOfPackage, colonIndex);
+        target = rawLabel.substring(colonIndex + 1);
+      } else if (pkgIsAbsolute) {
+        // Special case: the label "[@repo]//foo/bar" is synonymous with "[@repo]//foo/bar:bar".
+        pkg = rawLabel.substring(startOfPackage);
+        // The target name is the last package segment (works even if `pkg` contains no slash)
+        target = pkg.substring(pkg.lastIndexOf('/') + 1);
+      } else {
+        // Special case: the label "foo/bar" is synonymous with ":foo/bar".
+        pkg = "";
+        target = rawLabel.substring(startOfPackage);
+      }
+      return validateAndCreate(repo, pkgIsAbsolute, pkg, target, rawLabel);
+    }
+
+    @Nullable
+    private static String validateAndProcessRepoName(@Nullable String repo, String pkg)
+        throws LabelSyntaxException {
+      if (repo == null && ABSOLUTE_PACKAGE_NAMES.contains(pkg)) {
+        // These package names when used without a "@" part are always absolutely in the main repo.
+        return "";
+      }
+      if (repo == null) {
+        return null;
+      }
+      String error = RepositoryName.validate('@' + repo);
+      if (error != null) {
+        throw syntaxErrorf("invalid repository name '@%s': %s", repo, error);
+      }
+      return repo;
+    }
+
+    private static String validateAndProcessPackageName(String pkg, String target)
+        throws LabelSyntaxException {
+      String pkgError = LabelValidator.validatePackageName(pkg);
+      if (pkgError != null) {
+        throw syntaxErrorf(
+            "invalid package name '%s': %s%s", pkg, pkgError, perhapsYouMeantMessage(pkg, target));
+      }
+      return pkg;
+    }
+
+    void checkPkgIsAbsolute() throws LabelSyntaxException {
+      if (!pkgIsAbsolute) {
+        throw syntaxErrorf("invalid label '%s': absolute label must begin with '@' or '//'", raw);
+      }
+    }
+  }
+
+  @FormatMethod
+  static LabelSyntaxException syntaxErrorf(String format, Object... args) {
+    return new LabelSyntaxException(
+        StringUtilities.sanitizeControlChars(String.format(format, args)));
+  }
+
+  private static String perhapsYouMeantMessage(String pkg, String target) {
+    return pkg.endsWith('/' + target) ? " (perhaps you meant \":" + target + "\"?)" : "";
+  }
+
+  static String validateAndProcessTargetName(String pkg, String target)
+      throws LabelSyntaxException {
+    String targetError = LabelValidator.validateTargetName(target);
+    if (targetError != null) {
+      throw syntaxErrorf(
+          "invalid target name '%s': %s%s",
+          target, targetError, perhapsYouMeantMessage(pkg, target));
+    }
+    // TODO(bazel-team): This should be an error, but we can't make it one for legacy reasons.
+    if (target.endsWith("/.")) {
+      return target.substring(0, target.length() - 2);
+    }
+    return target;
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
index 3cbe4c446286ad..b2eda75ddc3491 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/PackageIdentifier.java
@@ -24,11 +24,8 @@
 import javax.annotation.concurrent.Immutable;
 
 /**
- * Uniquely identifies a package, given a repository name and a package's path fragment.
- *
- * <p>The repository the build is happening in is the <i>default workspace</i>, and is identified by
- * the workspace name "". Other repositories can be named in the WORKSPACE file. These workspaces
- * are prefixed by {@literal @}.
+ * Uniquely identifies a package. Contains the (canonical) name of the repository this package lives
+ * in, and the package's path fragment.
  */
 @AutoCodec
 @Immutable
@@ -114,44 +111,15 @@ private PackageIdentifier(RepositoryName repository, PathFragment pkgName) {
   }
 
   public static PackageIdentifier parse(String input) throws LabelSyntaxException {
-    return parse(input, /* repo= */ null, /* repositoryMapping= */ null);
-  }
-
-  public static PackageIdentifier parse(
-      String input, String repo, RepositoryMapping repositoryMapping) throws LabelSyntaxException {
-    String packageName;
-    int packageStartPos = input.indexOf("//");
-    if (repo != null) {
-      packageName = input;
-    } else if (input.startsWith("@") && packageStartPos > 0) {
-      repo = input.substring(0, packageStartPos);
-      packageName = input.substring(packageStartPos + 2);
-    } else if (input.startsWith("@")) {
-      throw new LabelSyntaxException("starts with a '@' but does not contain '//'");
-    } else if (packageStartPos == 0) {
-      repo = RepositoryName.DEFAULT_REPOSITORY;
-      packageName = input.substring(2);
-    } else {
-      repo = RepositoryName.DEFAULT_REPOSITORY;
-      packageName = input;
-    }
-
-    String error = RepositoryName.validate(repo);
-    if (error != null) {
-      throw new LabelSyntaxException(error);
-    }
-
-    error = LabelValidator.validatePackageName(packageName);
-    if (error != null) {
-      throw new LabelSyntaxException(error);
-    }
-
-    if (repositoryMapping == null) {
-      return create(repo, PathFragment.create(packageName));
+    if (input.contains(":")) {
+      throw LabelParser.syntaxErrorf("invalid package identifier '%s': contains ':'", input);
     }
-
-    return create(
-        repositoryMapping.get(RepositoryName.create(repo)), PathFragment.create(packageName));
+    LabelParser.Parts parts = LabelParser.Parts.parse(input + ":dummy_target");
+    RepositoryName repoName =
+        parts.repo == null
+            ? RepositoryName.MAIN
+            : RepositoryName.createFromValidStrippedName(parts.repo);
+    return create(repoName, PathFragment.create(parts.pkg));
   }
 
   public RepositoryName getRepository() {
@@ -175,8 +143,9 @@ public PathFragment getSourceRoot() {
    * this is in the main repository or siblingRepositoryLayout is true. Otherwise, returns
    * external/[repository name]/[pkgName].
    */
+  // TODO(bazel-team): Rename getDerivedArtifactPath or similar.
   public PathFragment getPackagePath(boolean siblingRepositoryLayout) {
-    return repository.isDefault() || repository.isMain() || siblingRepositoryLayout
+    return repository.isMain() || siblingRepositoryLayout
         ? pkgName
         : LabelConstants.EXTERNAL_PATH_PREFIX
             .getRelative(repository.strippedName())
@@ -195,30 +164,28 @@ public PathFragment getRunfilesPath() {
     return repository.getRunfilesPath().getRelative(pkgName);
   }
 
-  public PackageIdentifier makeAbsolute() {
-    if (!repository.isDefault()) {
-      return this;
-    }
-
-    return create(RepositoryName.MAIN, pkgName);
-  }
-
-  /** Returns the package in label syntax format. */
+  /**
+   * Returns the package in label syntax format.
+   *
+   * <p>Packages in the main repo are formatted without a repo qualifier.
+   */
+  // TODO(bazel-team): Maybe rename to "getDefaultForm"?
   public String getCanonicalForm() {
     String repository = getRepository().getCanonicalForm();
     return repository + "//" + getPackageFragment();
   }
 
   /**
-   * Returns the name of this package.
+   * Returns the package path, possibly qualified with a repository name.
    *
-   * <p>There are certain places that expect the path fragment as the package name ('foo/bar') as a
-   * package identifier. This isn't specific enough for packages in other repositories, so their
-   * stringified version is '@baz//foo/bar'.
+   * <p>Packages that live in the main repo are stringified without a "@" qualifier or "//"
+   * separator (e.g. "foo/bar"). All other packages include these (e.g. "@repo//foo/bar").
    */
+  // TODO(bazel-team): The absence of "//" for the main repo seems strange. Can we eliminate
+  // that disparity?
   @Override
   public String toString() {
-    return (repository.isDefault() || repository.isMain() ? "" : repository + "//") + pkgName;
+    return (repository.isMain() ? "" : repository + "//") + pkgName;
   }
 
   @Override
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryMapping.java b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryMapping.java
index 5e2bbe5460e727..54d1dca1a92dd7 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryMapping.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryMapping.java
@@ -79,11 +79,9 @@ public RepositoryMapping withAdditionalMappings(RepositoryMapping additionalMapp
   }
 
   public RepositoryName get(RepositoryName repositoryName) {
-    // 1. Default repo ("") should always map to default repo
-    // 2. @bazel_tools is a special repo that should be visible to all repositories.
-    // 3. @local_config_platform is a special repo that should be visible to all repositories.
-    if (repositoryName.equals(RepositoryName.DEFAULT)
-        || repositoryName.equals(RepositoryName.BAZEL_TOOLS)
+    // 1. @bazel_tools is a special repo that should be visible to all repositories.
+    // 2. @local_config_platform is a special repo that should be visible to all repositories.
+    if (repositoryName.equals(RepositoryName.BAZEL_TOOLS)
         || repositoryName.equals(RepositoryName.LOCAL_CONFIG_PLATFORM)) {
       return repositoryName;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
index e2edc6b2d1e6a6..4ea21107dde2b2 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/RepositoryName.java
@@ -32,11 +32,6 @@
 /** The name of an external repository. */
 public final class RepositoryName {
 
-  static final String DEFAULT_REPOSITORY = "";
-
-  @SerializationConstant
-  public static final RepositoryName DEFAULT = new RepositoryName(DEFAULT_REPOSITORY);
-
   @SerializationConstant
   public static final RepositoryName BAZEL_TOOLS = new RepositoryName("@bazel_tools");
 
@@ -71,10 +66,8 @@ public final class RepositoryName {
    * @throws LabelSyntaxException if the name is invalid
    */
   public static RepositoryName create(String name) throws LabelSyntaxException {
-    if (name.isEmpty()) {
-      return DEFAULT;
-    }
-    if (name.equals("@")) {
+    // TODO(b/200024947): Get rid of the '@'.
+    if (name.isEmpty() || name.equals("@")) {
       return MAIN;
     }
     try {
@@ -90,6 +83,12 @@ public static RepositoryName create(String name) throws LabelSyntaxException {
    * directory that has been created via getSourceRoot() or getPathUnderExecRoot().
    */
   public static RepositoryName createFromValidStrippedName(String name) {
+    if (name.isEmpty()) {
+      // NOTE(wyv): Without this `if` clause, a lot of Google-internal integration tests would start
+      //   failing. This suggests to me that something is comparing RepositoryName objects using
+      //   reference equality instead of #equals().
+      return MAIN;
+    }
     return repositoryNameCache.get("@" + name);
   }
 
@@ -231,6 +230,7 @@ public String getName() {
    * Returns the repository name, except that the main repo is conflated with the default repo
    * ({@code "@"} becomes the empty string).
    */
+  // TODO(bazel-team): Consider renaming to "getDefaultForm".
   public String getCanonicalForm() {
     return isMain() ? "" : name;
   }
@@ -243,7 +243,7 @@ public String getCanonicalForm() {
    * __main__), instead of "$execroot/external/repo".
    */
   public PathFragment getExecPath(boolean siblingRepositoryLayout) {
-    if (isDefault() || isMain()) {
+    if (isMain()) {
       return PathFragment.EMPTY_FRAGMENT;
     }
     PathFragment prefix =
@@ -258,8 +258,9 @@ public PathFragment getExecPath(boolean siblingRepositoryLayout) {
    */
   // TODO(kchodorow): remove once execroot is reorg-ed.
   public PathFragment getRunfilesPath() {
-    return isDefault() || isMain()
-        ? PathFragment.EMPTY_FRAGMENT : PathFragment.create("..").getRelative(strippedName());
+    return isMain()
+        ? PathFragment.EMPTY_FRAGMENT
+        : PathFragment.create("..").getRelative(strippedName());
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/cmdline/TargetPattern.java b/src/main/java/com/google/devtools/build/lib/cmdline/TargetPattern.java
index 8f830057cf9f95..8cfdf70761dbd1 100644
--- a/src/main/java/com/google/devtools/build/lib/cmdline/TargetPattern.java
+++ b/src/main/java/com/google/devtools/build/lib/cmdline/TargetPattern.java
@@ -421,7 +421,6 @@ private TargetsInPackage(
         boolean rulesOnly,
         boolean checkWildcardConflict) {
       super(originalPattern);
-      Preconditions.checkArgument(!packageIdentifier.getRepository().isDefault());
       this.packageIdentifier = packageIdentifier;
       this.suffix = Preconditions.checkNotNull(suffix);
       this.wasOriginallyAbsolute = wasOriginallyAbsolute;
@@ -551,7 +550,6 @@ public static final class TargetsBelowDirectory extends TargetPattern {
     private TargetsBelowDirectory(
         String originalPattern, PackageIdentifier directory, boolean rulesOnly) {
       super(originalPattern);
-      Preconditions.checkArgument(!directory.getRepository().isDefault());
       this.directory = Preconditions.checkNotNull(directory);
       this.rulesOnly = rulesOnly;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/packages/AbstractAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/packages/AbstractAttributeMapper.java
index df8c11c9248e1d..60a28ec8961fdf 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/AbstractAttributeMapper.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/AbstractAttributeMapper.java
@@ -185,8 +185,7 @@ private void visitLabels(
     Type.LabelVisitor visitor =
         (label, attribute) -> {
           if (label != null) {
-            Label absoluteLabel = ruleLabel.resolveRepositoryRelative(label);
-            consumer.accept(attribute, absoluteLabel);
+            consumer.accept(attribute, label);
           }
         };
     for (Attribute attribute : attributes) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/AspectDefinition.java b/src/main/java/com/google/devtools/build/lib/packages/AspectDefinition.java
index 44f7a6fd4ef97e..09a84325d70093 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/AspectDefinition.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/AspectDefinition.java
@@ -222,11 +222,6 @@ public boolean requires(Aspect maybeRequiredAspect) {
     return requiredAspectClasses.contains(maybeRequiredAspect.getAspectClass());
   }
 
-  @Nullable
-  private static Label maybeGetRepositoryRelativeLabel(Rule from, @Nullable Label label) {
-    return label == null ? null : from.getLabel().resolveRepositoryRelative(label);
-  }
-
   /** Collects all attribute labels from the specified aspectDefinition. */
   public static void addAllAttributesOfAspect(
       final Rule from,
@@ -243,11 +238,10 @@ public static void forEachLabelDepFromAllAttributesOfAspect(
       BiConsumer<Attribute, Label> consumer) {
     LabelVisitor labelVisitor =
         (label, aspectAttribute) -> {
-          Label repositoryRelativeLabel = maybeGetRepositoryRelativeLabel(from, label);
-          if (repositoryRelativeLabel == null) {
+          if (label == null) {
             return;
           }
-          consumer.accept(aspectAttribute, repositoryRelativeLabel);
+          consumer.accept(aspectAttribute, label);
         };
     for (Attribute aspectAttribute : aspect.getDefinition().attributes.values()) {
       if (!dependencyFilter.test(aspect, aspectAttribute)) {
diff --git a/src/main/java/com/google/devtools/build/lib/packages/BuildType.java b/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
index 746d6963946b0b..452f7aa5db5529 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/BuildType.java
@@ -249,8 +249,7 @@ public Label convert(Object x, Object what, Object context) throws ConversionExc
         String str = (String) x;
         // TODO(b/110101445): check if context is ever actually null
         if (context == null) {
-          return Label.parseAbsolute(
-              str, /* defaultToMain= */ false, /* repositoryMapping= */ ImmutableMap.of());
+          return Label.parseAbsolute(str, /* repositoryMapping= */ ImmutableMap.of());
           // TODO(b/110308446): remove instances of context being a Label
         } else if (context instanceof Label) {
           return ((Label) context).getRelativeWithRemapping(str, ImmutableMap.of());
diff --git a/src/main/java/com/google/devtools/build/lib/packages/ConfiguredAttributeMapper.java b/src/main/java/com/google/devtools/build/lib/packages/ConfiguredAttributeMapper.java
index a258d93495c46c..70e72d3fd3d0a0 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/ConfiguredAttributeMapper.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/ConfiguredAttributeMapper.java
@@ -184,8 +184,7 @@ private <T> ConfigKeyAndValue<T> resolveSelector(String attributeName, Selector<
         continue;
       }
 
-      ConfigMatchingProvider curCondition =
-          configConditions.get(getLabel().resolveRepositoryRelative(selectorKey));
+      ConfigMatchingProvider curCondition = configConditions.get(selectorKey);
       if (curCondition == null) {
         // This can happen if the rule is in error
         continue;
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageGroupsRuleVisibility.java b/src/main/java/com/google/devtools/build/lib/packages/PackageGroupsRuleVisibility.java
index dbf46cb4c62953..934ed6f103d8c4 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageGroupsRuleVisibility.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageGroupsRuleVisibility.java
@@ -27,18 +27,18 @@ public class PackageGroupsRuleVisibility implements RuleVisibility {
   private final PackageGroupContents directPackages;
   private final List<Label> declaredLabels;
 
-  private PackageGroupsRuleVisibility(Label ruleLabel, List<Label> labels) {
+  // TODO(b/200024947): Remove the unused argument.
+  private PackageGroupsRuleVisibility(Label unusedRuleLabel, List<Label> labels) {
     declaredLabels = ImmutableList.copyOf(labels);
     ImmutableList.Builder<PackageSpecification> directPackageBuilder = ImmutableList.builder();
     ImmutableList.Builder<Label> packageGroupBuilder = ImmutableList.builder();
 
     for (Label label : labels) {
-      Label resolved = ruleLabel.resolveRepositoryRelative(label);
-      PackageSpecification specification = PackageSpecification.fromLabel(resolved);
+      PackageSpecification specification = PackageSpecification.fromLabel(label);
       if (specification != null) {
         directPackageBuilder.add(specification);
       } else {
-        packageGroupBuilder.add(resolved);
+        packageGroupBuilder.add(label);
       }
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/packages/PackageSpecification.java b/src/main/java/com/google/devtools/build/lib/packages/PackageSpecification.java
index 318cab60cbe08d..a099ccf6e271a6 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/PackageSpecification.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/PackageSpecification.java
@@ -120,7 +120,7 @@ private static PackageSpecification fromStringPositive(RepositoryName repository
       throw new InvalidPackageSpecificationException(
           String.format("invalid package name '%s': %s", spec, e.getMessage()));
     }
-    Verify.verify(packageId.getRepository().isDefault());
+    Verify.verify(packageId.getRepository().isMain());
 
     PackageIdentifier packageIdForSpecifiedRepository =
         PackageIdentifier.create(repositoryName, packageId.getPackageFragment());
diff --git a/src/main/java/com/google/devtools/build/lib/pkgcache/PackageOptions.java b/src/main/java/com/google/devtools/build/lib/pkgcache/PackageOptions.java
index ca6f59321831a1..b130b52585a2a2 100644
--- a/src/main/java/com/google/devtools/build/lib/pkgcache/PackageOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/pkgcache/PackageOptions.java
@@ -225,13 +225,9 @@ public String getTypeDescription() {
   }
 
   public ImmutableSet<PackageIdentifier> getDeletedPackages() {
-    if (deletedPackages == null || deletedPackages.isEmpty()) {
+    if (deletedPackages == null) {
       return ImmutableSet.of();
     }
-    ImmutableSet.Builder<PackageIdentifier> newDeletedPackages = ImmutableSet.builder();
-    for (PackageIdentifier pkg : deletedPackages) {
-      newDeletedPackages.add(pkg.makeAbsolute());
-    }
-    return newDeletedPackages.build();
+    return ImmutableSet.copyOf(deletedPackages);
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java b/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
index 985bc35f10924e..c5c4be5cd050e0 100644
--- a/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
+++ b/src/main/java/com/google/devtools/build/lib/pkgcache/PathPackageLocator.java
@@ -14,7 +14,6 @@
 package com.google.devtools.build.lib.pkgcache;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
 import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableList;
 import com.google.devtools.build.lib.cmdline.LabelConstants;
@@ -106,7 +105,6 @@ public Path getPackageBuildFile(PackageIdentifier packageName) throws NoSuchPack
   public Path getPackageBuildFileNullable(
       PackageIdentifier packageIdentifier,
       AtomicReference<? extends UnixGlob.FilesystemCalls> cache) {
-    Preconditions.checkArgument(!packageIdentifier.getRepository().isDefault());
     if (packageIdentifier.getRepository().isMain()) {
       for (BuildFileName buildFileName : buildFilesByPriority) {
         Path buildFilePath =
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
index 6a0b0ad71b2cce..f2005eb1df1536 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java
@@ -1033,8 +1033,7 @@ private CcCompilationContext.Builder initializeCcCompilationContext(RuleContext
     ccCompilationContextBuilder.addFrameworkIncludeDirs(frameworkIncludeDirs);
 
     boolean external =
-        !repositoryName.isDefault()
-            && !repositoryName.isMain()
+        !repositoryName.isMain()
             && featureConfiguration.isEnabled(CppRuleClasses.EXTERNAL_INCLUDE_PATHS);
 
     if (external) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileActionBuilder.java
index 0a8711914b990a..20a9da7968bdd5 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaCompileActionBuilder.java
@@ -322,7 +322,7 @@ private CustomCommandLine buildParamFileContents(ImmutableList<String> javacOpts
     }
     if (targetLabel != null) {
       result.add("--target_label");
-      if (targetLabel.getRepository().isDefault() || targetLabel.getRepository().isMain()) {
+      if (targetLabel.getRepository().isMain()) {
         result.addLabel(targetLabel);
       } else {
         // @-prefixed strings will be assumed to be filenames and expanded by
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
index e079e1ae087073..c322839b70f8f2 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaHeaderCompileActionBuilder.java
@@ -351,7 +351,7 @@ public void build(JavaToolchainProvider javaToolchain) throws InterruptedExcepti
 
     if (targetLabel != null) {
       commandLine.add("--target_label");
-      if (targetLabel.getRepository().isDefault() || targetLabel.getRepository().isMain()) {
+      if (targetLabel.getRepository().isMain()) {
         commandLine.addLabel(targetLabel);
       } else {
         // @-prefixed strings will be assumed to be params filenames and expanded,
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaRuntime.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaRuntime.java
index 86c3228f06dc58..63b15b604aba22 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaRuntime.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaRuntime.java
@@ -127,7 +127,7 @@ private static boolean isJavaBinary(PathFragment path) {
   }
 
   static PathFragment defaultJavaHome(Label javabase, boolean siblingRepositoryLayout) {
-    if (javabase.getRepository().isDefault()) {
+    if (javabase.getRepository().isMain()) {
       return javabase.getPackageFragment();
     }
     return javabase.getPackageIdentifier().getExecPath(siblingRepositoryLayout);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/OneVersionCheckActionBuilder.java b/src/main/java/com/google/devtools/build/lib/rules/java/OneVersionCheckActionBuilder.java
index 2e4a887c345e90..f55b9a69fb1c64 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/OneVersionCheckActionBuilder.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/OneVersionCheckActionBuilder.java
@@ -129,7 +129,7 @@ static VectorArg<String> jarAndTargetVectorArg(NestedSet<Artifact> jarsToCheck)
 
   private static String getArtifactOwnerGeneralizedLabel(Artifact artifact) {
     Label label = checkNotNull(artifact.getOwnerLabel(), artifact);
-    return label.getRepository().isDefault() || label.getRepository().isMain()
+    return label.getRepository().isMain()
         ? label.toString()
         // Escape '@' prefix for .params file.
         : "@" + label;
diff --git a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
index 2cd36863d86dd4..0f14bfdb907ca7 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/repository/RepositoryFunction.java
@@ -264,14 +264,6 @@ static boolean verifyMarkerDataForFiles(
 
   public static RootedPath getRootedPathFromLabel(Label label, Environment env)
       throws InterruptedException, EvalException {
-    // Look for package.
-    if (label.getRepository().isDefault()) {
-      try {
-        label = Label.create(label.getPackageIdentifier().makeAbsolute(), label.getName());
-      } catch (LabelSyntaxException e) {
-        throw new AssertionError(e); // Can't happen because the input label is valid
-      }
-    }
     SkyKey pkgSkyKey = PackageLookupValue.key(label.getPackageIdentifier());
     PackageLookupValue pkgLookupValue = (PackageLookupValue) env.getValue(pkgSkyKey);
     if (pkgLookupValue == null) {
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
index a2247fa0736881..3de8e895e7b4cc 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/BzlLoadFunction.java
@@ -885,8 +885,6 @@ static ImmutableList<Label> getLoadLabels(
       ImmutableList<Pair<String, Location>> loads,
       PackageIdentifier base,
       RepositoryMapping repoMapping) {
-    Preconditions.checkArgument(!base.getRepository().isDefault());
-
     // It's redundant that getRelativeWithRemapping needs a Label;
     // a PackageIdentifier should suffice. Make one here.
     Label buildLabel = getBUILDLabel(base);
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
index 599dfe96c9fd8e..72facd81c3e053 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ConfiguredTargetFunction.java
@@ -739,9 +739,7 @@ static ConfigConditions getConfigConditions(
 
     // Collect the labels of the configured targets we need to resolve.
     List<Label> configLabels =
-        attrs.get(RuleClass.CONFIG_SETTING_DEPS_ATTRIBUTE, BuildType.LABEL_LIST).stream()
-            .map(configLabel -> target.getLabel().resolveRepositoryRelative(configLabel))
-            .collect(Collectors.toList());
+        attrs.get(RuleClass.CONFIG_SETTING_DEPS_ATTRIBUTE, BuildType.LABEL_LIST);
     if (configLabels.isEmpty()) {
       return ConfigConditions.EMPTY;
     }
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java
index 0323f6e6bb725b..39449b2e68cdd3 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ContainingPackageLookupValue.java
@@ -57,7 +57,6 @@ public String getReasonForNoContainingPackage() {
 
   public static Key key(PackageIdentifier id) {
     Preconditions.checkArgument(!id.getPackageFragment().isAbsolute(), id);
-    Preconditions.checkArgument(!id.getRepository().isDefault(), id);
     return Key.create(id);
   }
 
@@ -90,7 +89,7 @@ static String getErrorMessageForLabelCrossingPackageBoundary(
                   labelNameFragment.segmentCount())
               : label.toPathFragment().relativeTo(containingPkgFragment);
       message += "; perhaps you meant to put the colon here: '";
-      if (containingPkg.getRepository().isDefault() || containingPkg.getRepository().isMain()) {
+      if (containingPkg.getRepository().isMain()) {
         message += "//";
       }
       message += containingPkg + ":" + labelNameInContainingPackage + "'?";
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
index c68f03bc9fe052..74ae317dea92d6 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageFunction.java
@@ -13,7 +13,6 @@
 // limitations under the License.
 package com.google.devtools.build.lib.skyframe;
 
-import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
@@ -656,8 +655,6 @@ static ImmutableMap<String, Module> loadBzlModules(
       List<BzlLoadValue.Key> keys,
       @Nullable BzlLoadFunction bzlLoadFunctionForInlining)
       throws NoSuchPackageException, InterruptedException {
-    checkArgument(!packageId.getRepository().isDefault());
-
     List<BzlLoadValue> bzlLoads;
     try {
       bzlLoads =
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java
index c5b7b577619bb6..562ce5e335b4d1 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageLookupValue.java
@@ -126,7 +126,6 @@ public static SkyKey key(PathFragment directory) {
   }
 
   public static Key key(PackageIdentifier pkgIdentifier) {
-    Preconditions.checkArgument(!pkgIdentifier.getRepository().isDefault());
     return Key.create(pkgIdentifier);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
index 180772577717a5..0172abbd6ab1f7 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/PackageValue.java
@@ -57,7 +57,6 @@ public String toString() {
   }
 
   public static Key key(PackageIdentifier pkgIdentifier) {
-    Preconditions.checkArgument(!pkgIdentifier.getRepository().isDefault());
     return Key.create(pkgIdentifier);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ProcessPackageDirectory.java b/src/main/java/com/google/devtools/build/lib/skyframe/ProcessPackageDirectory.java
index 23712d1d6ca480..9dd2c4f240c35c 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/ProcessPackageDirectory.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ProcessPackageDirectory.java
@@ -123,7 +123,7 @@ public ProcessPackageDirectoryResult getPackageExistenceAndSubdirDeps(
 
     PackageIdentifier packageId = PackageIdentifier.create(repositoryName, rootRelativePath);
 
-    if ((packageId.getRepository().isDefault() || packageId.getRepository().isMain())
+    if (packageId.getRepository().isMain()
         && fileValue.isSymlink()
         && fileValue
             .getUnresolvedLinkTarget()
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePkgKey.java b/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePkgKey.java
index 25054f849a5b59..d1924148db4d7f 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePkgKey.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/RecursivePkgKey.java
@@ -42,7 +42,6 @@ public RecursivePkgKey(
       RootedPath rootedPath,
       ImmutableSet<PathFragment> excludedPaths) {
     PathFragment.checkAllPathsAreUnder(excludedPaths, rootedPath.getRootRelativePath());
-    Preconditions.checkState(!repositoryName.isDefault());
     this.repositoryName = repositoryName;
     this.rootedPath = Preconditions.checkNotNull(rootedPath);
     this.excludedPaths = Preconditions.checkNotNull(excludedPaths);
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
index 5267d3c60fb768..88470c4121fb31 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeExecutor.java
@@ -2662,8 +2662,6 @@ Package getPackage(ExtendedEventHandler eventHandler, PackageIdentifier pkgName)
 
     /** Returns whether the given package should be consider deleted and thus should be ignored. */
     public boolean isPackageDeleted(PackageIdentifier packageName) {
-      Preconditions.checkState(
-          !packageName.getRepository().isDefault(), "package must be absolute: %s", packageName);
       return deletedPackages.get().contains(packageName);
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTargetKey.java b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTargetKey.java
index 7fad37ebac00c4..04a942a45e5325 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTargetKey.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTargetKey.java
@@ -31,7 +31,6 @@ public final class TransitiveTargetKey implements SkyKey {
   public static final SkyFunctionName NAME = SkyFunctionName.createHermetic("TRANSITIVE_TARGET");
 
   public static TransitiveTargetKey of(Label label) {
-    Preconditions.checkArgument(!label.getRepository().isDefault());
     return new TransitiveTargetKey(label);
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
index 77ffabdfeeb94f..def4ca5b779c9e 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TransitiveTraversalValue.java
@@ -150,7 +150,6 @@ public int hashCode() {
 
   @ThreadSafe
   public static SkyKey key(Label label) {
-    Preconditions.checkArgument(!label.getRepository().isDefault());
     return label;
   }
 
diff --git a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeStarlarkRuleFunctionsApi.java b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeStarlarkRuleFunctionsApi.java
index ac4413a667f9eb..4a95d2dea09d21 100644
--- a/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeStarlarkRuleFunctionsApi.java
+++ b/src/main/java/com/google/devtools/build/skydoc/fakebuildapi/FakeStarlarkRuleFunctionsApi.java
@@ -171,7 +171,6 @@ public Label label(String labelString, StarlarkThread thread) throws EvalExcepti
     try {
       return Label.parseAbsolute(
           labelString,
-          /* defaultToMain= */ false,
           /* repositoryMapping= */ ImmutableMap.of());
     } catch (LabelSyntaxException e) {
       throw Starlark.errorf("Illegal absolute label syntax: %s", labelString);
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/test/TestActionBuilderTest.java b/src/test/java/com/google/devtools/build/lib/analysis/test/TestActionBuilderTest.java
index 9df31fdabead55..731b1fe92a14e3 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/test/TestActionBuilderTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/test/TestActionBuilderTest.java
@@ -16,7 +16,6 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
 import com.google.common.eventbus.EventBus;
 import com.google.devtools.build.lib.actions.Artifact;
@@ -216,12 +215,7 @@ public void testAspectOverNonExpandingTestSuitesVisitsImplicitTests() throws Exc
     ConfiguredAspect aspectValue =
         Iterables.getOnlyElement(analysisResult.getAspectsMap().values());
     StarlarkProvider.Key key =
-        new StarlarkProvider.Key(
-            Label.parseAbsolute(
-                "//:aspect.bzl",
-                /* defaultToMain= */ true,
-                /* repositoryMapping= */ ImmutableMap.of()),
-            "StructImpl");
+        new StarlarkProvider.Key(Label.parseAbsoluteUnchecked("//:aspect.bzl"), "StructImpl");
     StructImpl info = (StructImpl) aspectValue.get(key);
     assertThat(((Depset) info.getValue("labels")).getSet(String.class).toList())
         .containsExactly("//:suite", "//:test_a", "//:test_b");
@@ -254,12 +248,7 @@ public void testAspectOverNonExpandingTestSuitesVisitsExplicitTests() throws Exc
     ConfiguredAspect aspectValue =
         Iterables.getOnlyElement(analysisResult.getAspectsMap().values());
     StarlarkProvider.Key key =
-        new StarlarkProvider.Key(
-            Label.parseAbsolute(
-                "//:aspect.bzl",
-                /* defaultToMain= */ true,
-                /* repositoryMapping= */ ImmutableMap.of()),
-            "StructImpl");
+        new StarlarkProvider.Key(Label.parseAbsoluteUnchecked("//:aspect.bzl"), "StructImpl");
     StructImpl info = (StructImpl) aspectValue.get(key);
     assertThat(((Depset) info.getValue("labels")).getSet(String.class).toList())
         .containsExactly("//:suite", "//:test_b");
@@ -288,12 +277,7 @@ public void testAspectOverExpandingTestSuitesDoesNotVisitSuite() throws Exceptio
             /* doAnalysis= */ true,
             new EventBus());
     final StarlarkProvider.Key key =
-        new StarlarkProvider.Key(
-            Label.parseAbsolute(
-                "//:aspect.bzl",
-                /* defaultToMain= */ true,
-                /* repositoryMapping= */ ImmutableMap.of()),
-            "StructImpl");
+        new StarlarkProvider.Key(Label.parseAbsoluteUnchecked("//:aspect.bzl"), "StructImpl");
 
     List<String> labels = new ArrayList<>();
     for (ConfiguredAspect a : analysisResult.getAspectsMap().values()) {
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
index c8d224d772d1ee..0e6348a058a3e9 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
@@ -163,7 +163,6 @@
 import com.google.devtools.build.lib.skyframe.SkyframeExecutor;
 import com.google.devtools.build.lib.skyframe.StarlarkBuiltinsValue;
 import com.google.devtools.build.lib.skyframe.TargetPatternPhaseValue;
-import com.google.devtools.build.lib.testutil.BlazeTestUtils;
 import com.google.devtools.build.lib.testutil.FoundationTestCase;
 import com.google.devtools.build.lib.testutil.SkyframeExecutorTestHelper;
 import com.google.devtools.build.lib.testutil.TestConstants;
@@ -1020,8 +1019,7 @@ protected ConfiguredTarget getConfiguredTarget(String label, BuildConfigurationV
   @Nullable
   protected ConfiguredTarget getConfiguredTarget(Label label, BuildConfigurationValue config) {
     try {
-      return view.getConfiguredTargetForTesting(
-          reporter, BlazeTestUtils.convertLabel(label), config);
+      return view.getConfiguredTargetForTesting(reporter, label, config);
     } catch (InvalidConfigurationException
         | StarlarkTransition.TransitionException
         | InterruptedException e) {
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
index 30b830e2cb1c7e..1fe0dc07f9ff51 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/LabelTest.java
@@ -218,20 +218,6 @@ public void testGetRelativeWithRemoteRepoToDefaultRepo() throws Exception {
     assertThat(relative.getName()).isEqualTo("y");
   }
 
-  @Test
-  public void testGetRepositoryRelative() throws Exception {
-    Label defaultBase = Label.parseAbsolute("//foo/bar:baz", ImmutableMap.of());
-    Label repoBase = Label.parseAbsolute("@repo//foo/bar:baz", ImmutableMap.of());
-    Label mainBase = Label.parseAbsolute("@//foo/bar:baz", ImmutableMap.of());
-    Label externalTarget = Label.parseAbsolute("//external:target", ImmutableMap.of());
-    Label l = defaultBase.resolveRepositoryRelative(externalTarget);
-    assertThat(l.getRepository().isMain()).isTrue();
-    assertThat(l.getPackageName()).isEqualTo("external");
-    assertThat(l.getName()).isEqualTo("target");
-    assertThat(repoBase.resolveRepositoryRelative(externalTarget)).isEqualTo(l);
-    assertThat(mainBase.resolveRepositoryRelative(externalTarget)).isEqualTo(l);
-  }
-
   @Test
   public void testFactory() throws Exception {
     Label l = Label.create("foo/bar", "quux");
@@ -422,7 +408,9 @@ public void testInvalidRepo() throws Exception {
             () -> Label.parseAbsolute("foo//bar/baz:bat/boo", ImmutableMap.of()));
     assertThat(e)
         .hasMessageThat()
-        .isEqualTo("invalid repository name 'foo': workspace names must start with '@'");
+        .isEqualTo(
+            "invalid package name 'foo//bar/baz': package names may not contain '//' path"
+                + " separators");
   }
 
   @Test
diff --git a/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryNameTest.java b/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryNameTest.java
index 6ab1ee8b477f23..fc3141a6dfba3f 100644
--- a/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryNameTest.java
+++ b/src/test/java/com/google/devtools/build/lib/cmdline/RepositoryNameTest.java
@@ -37,7 +37,8 @@ public void assertNotValid(String name, String expectedMessage) {
   @Test
   public void testValidateRepositoryName() throws Exception {
     assertThat(RepositoryName.create("@foo").toString()).isEqualTo("@foo");
-    assertThat(RepositoryName.create("").toString()).isEmpty();
+    assertThat(RepositoryName.create("").toString()).isEqualTo("@");
+    assertThat(RepositoryName.create("")).isSameInstanceAs(RepositoryName.MAIN);
     assertThat(RepositoryName.create("@foo_bar").toString()).isEqualTo("@foo_bar");
     assertThat(RepositoryName.create("@foo-bar").toString()).isEqualTo("@foo-bar");
     assertThat(RepositoryName.create("@foo.bar").toString()).isEqualTo("@foo.bar");
diff --git a/src/test/java/com/google/devtools/build/lib/pkgcache/LoadingPhaseRunnerTest.java b/src/test/java/com/google/devtools/build/lib/pkgcache/LoadingPhaseRunnerTest.java
index 64f8f0311309a3..eaac956da2ec72 100644
--- a/src/test/java/com/google/devtools/build/lib/pkgcache/LoadingPhaseRunnerTest.java
+++ b/src/test/java/com/google/devtools/build/lib/pkgcache/LoadingPhaseRunnerTest.java
@@ -1171,7 +1171,8 @@ public void testPatternEndingWithSingleSlashIsError() {
   public void testPatternStartingWithDotDotSlash() {
     expectError(
         "../foo",
-        "Bad target pattern '../foo': package name component contains only '.' characters");
+        "Bad target pattern '../foo': invalid package name '..': package name component contains"
+            + " only '.' characters");
   }
 
   private void runTestPackageLoadingError(boolean keepGoing, String... patterns) throws Exception {
diff --git a/src/test/java/com/google/devtools/build/lib/query2/testutil/AbstractQueryTest.java b/src/test/java/com/google/devtools/build/lib/query2/testutil/AbstractQueryTest.java
index 0dd74745994aef..9d0f1cba9ba57e 100644
--- a/src/test/java/com/google/devtools/build/lib/query2/testutil/AbstractQueryTest.java
+++ b/src/test/java/com/google/devtools/build/lib/query2/testutil/AbstractQueryTest.java
@@ -76,11 +76,6 @@ public abstract class AbstractQueryTest<T> {
 
   private static final String DEFAULT_UNIVERSE = "//...:*";
 
-  protected static final String BAD_PACKAGE_NAME =
-      "package names may contain "
-          + "A-Z, a-z, 0-9, or any of ' !\"#$%&'()*+,-./;<=>?[]^_`{|}~' "
-          + "(most 7-bit ascii characters except 0-31, 127, ':', or '\\')";
-
   protected MockToolsConfig mockToolsConfig;
   protected QueryHelper<T> helper;
   protected AnalysisMock analysisMock;
@@ -317,7 +312,11 @@ public void testBadTargetLiterals() throws Exception {
   protected final void checkResultofBadTargetLiterals(String message, FailureDetail failureDetail) {
     assertThat(failureDetail.getTargetPatterns().getCode())
         .isEqualTo(TargetPatterns.Code.LABEL_SYNTAX_ERROR);
-    assertThat(message).isEqualTo("Invalid package name 'bad:*': " + BAD_PACKAGE_NAME);
+    // TODO(bazel-team): This error message could use some improvement. It's verbose (duplicate
+    //   message) and shows an extra "@" that wasn't in the input.
+    assertThat(message)
+        .isEqualTo(
+            "Invalid package name 'bad:*': invalid package identifier '@//bad:*': contains ':'");
   }
 
   @Test
diff --git a/src/test/java/com/google/devtools/build/lib/rules/LabelBuildSettingTest.java b/src/test/java/com/google/devtools/build/lib/rules/LabelBuildSettingTest.java
index 52386c89807b48..0e1afdae573c80 100644
--- a/src/test/java/com/google/devtools/build/lib/rules/LabelBuildSettingTest.java
+++ b/src/test/java/com/google/devtools/build/lib/rules/LabelBuildSettingTest.java
@@ -281,6 +281,6 @@ public void transitionsDontAllowRelativeLabels() throws Exception {
         "rule_with_transition(name = 'buildme')");
     reporter.removeHandler(failFastHandler);
     assertThat(getConfiguredTarget("//test:buildme")).isNull();
-    assertContainsEvent("invalid label: :other_rule");
+    assertContainsEvent("invalid label ':other_rule': absolute label must begin with '@' or '//'");
   }
 }
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/serialization/RepositoryNameCodecTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/serialization/RepositoryNameCodecTest.java
index f9bfe33929f1c6..aeaeedac23b6d8 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/serialization/RepositoryNameCodecTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/serialization/RepositoryNameCodecTest.java
@@ -26,7 +26,6 @@ public class RepositoryNameCodecTest {
   @Test
   public void testCodec() throws Exception {
     new SerializationTester(
-            RepositoryName.create(RepositoryName.DEFAULT.getName()),
             RepositoryName.create(RepositoryName.MAIN.getName()),
             RepositoryName.create("@externalandshouldntexistinthisworkspace"))
         .runTests();
diff --git a/src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleClassFunctionsTest.java b/src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleClassFunctionsTest.java
index fbecb9450ce8ea..b2f580fb7c068b 100644
--- a/src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleClassFunctionsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleClassFunctionsTest.java
@@ -687,16 +687,17 @@ public void testLabelAttrDefaultValueAsString() throws Exception {
   public void testLabelAttrDefaultValueAsStringBadValue() throws Exception {
     ev.checkEvalErrorContains(
         "invalid label '/foo:bar' in parameter 'default' of attribute 'label': "
-            + "invalid target name '/foo:bar'",
+            + "invalid package name '/foo': package names may not start with '/'",
         "attr.label(default = '/foo:bar')");
 
     ev.checkEvalErrorContains(
         "invalid label '/bar:foo' in element 1 of parameter 'default' of attribute "
-            + "'label_list': invalid target name '/bar:foo'",
+            + "'label_list': invalid package name '/bar': package names may not start with '/'",
         "attr.label_list(default = ['//foo:bar', '/bar:foo'])");
 
     ev.checkEvalErrorContains(
-        "invalid label '/bar:foo' in dict key element: invalid target name '/bar:foo'",
+        "invalid label '/bar:foo' in dict key element: invalid package name '/bar': "
+            + "package names may not start with '/'",
         "attr.label_keyed_string_dict(default = {'//foo:bar': 'a', '/bar:foo': 'b'})");
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/testutil/BlazeTestUtils.java b/src/test/java/com/google/devtools/build/lib/testutil/BlazeTestUtils.java
index b6b83fac334a96..452d185c3f4b5e 100644
--- a/src/test/java/com/google/devtools/build/lib/testutil/BlazeTestUtils.java
+++ b/src/test/java/com/google/devtools/build/lib/testutil/BlazeTestUtils.java
@@ -16,8 +16,6 @@
 
 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
-import com.google.devtools.build.lib.cmdline.Label;
-import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
 import com.google.devtools.build.lib.vfs.FileSystemUtils;
 import com.google.devtools.build.lib.vfs.Path;
 import java.io.File;
@@ -85,16 +83,6 @@ public static void changeModtime(Path path)
     } while (path.getLastModifiedTime() == prevMtime);
   }
 
-  public static Label convertLabel(Label label) {
-    try {
-      return label.getRepository().isDefault()
-          ? Label.create(label.getPackageIdentifier().makeAbsolute(), label.getName())
-          : label;
-    } catch (LabelSyntaxException e) {
-      throw new IllegalStateException(e);
-    }
-  }
-
   /**
    * Creates a list of arguments to pass to Bazel, with flags necessary for Bazel to work properly
    * appended to the original {@code args} array.