diff --git a/protobuf/protoeditor-core/src/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProvider.java b/protobuf/protoeditor-core/src/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProvider.java
new file mode 100644
index 00000000000..b020ee7a6f3
--- /dev/null
+++ b/protobuf/protoeditor-core/src/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProvider.java
@@ -0,0 +1,76 @@
+package com.intellij.protobuf.lang.resolve;
+
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.roots.AdditionalLibraryRootsProvider;
+import com.intellij.openapi.roots.SyntheticLibrary;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.psi.search.GlobalSearchScope;
+import com.intellij.psi.search.GlobalSearchScopesCore;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.*;
+
+public class AdditionalLibrariesFileResolveProvider implements FileResolveProvider {
+    @NotNull
+    @Override
+    public Collection<ChildEntry> getChildEntries(@NotNull String path, @NotNull Project project) {
+        VirtualFile pathFile = findFile(path, project);
+        if (pathFile == null || !pathFile.isDirectory()) {
+            return Collections.emptyList();
+        }
+        VirtualFile[] children = pathFile.getChildren();
+        if (children == null) {
+            return Collections.emptyList();
+        }
+
+        Set<ChildEntry> results = new HashSet<>();
+
+        for (VirtualFile child : children) {
+            if (PROTO_AND_DIRECTORY_FILTER.accept(child)) {
+                results.add(new ChildEntry(child.getName(), child.isDirectory()));
+            }
+        }
+        return results;
+    }
+
+    @Nullable
+    @Override
+    public VirtualFile findFile(@NotNull String path, @NotNull Project project) {
+        for (AdditionalLibraryRootsProvider provider : AdditionalLibraryRootsProvider.EP_NAME.getExtensionList()) {
+            for (SyntheticLibrary library : provider.getAdditionalProjectLibraries(project)) {
+                for (VirtualFile sourceRoot : library.getSourceRoots()) {
+                    if (sourceRoot.isDirectory()) {
+                        VirtualFile pbFile = sourceRoot.findFileByRelativePath(path);
+                        if (pbFile != null) {
+                            return pbFile;
+                        }
+                    }
+                    if (sourceRoot.getPath().endsWith(path)) {
+                        return sourceRoot;
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    @Nullable
+    @Override
+    public VirtualFile getDescriptorFile(@NotNull Project project) {
+        return null;
+    }
+
+    @NotNull
+    @Override
+    public GlobalSearchScope getSearchScope(@NotNull Project project) {
+        VirtualFile[] roots = AdditionalLibraryRootsProvider.EP_NAME.getExtensionList().stream()
+                .map(provider -> provider.getAdditionalProjectLibraries(project))
+                .flatMap(Collection::stream)
+                .map(SyntheticLibrary::getSourceRoots)
+                .flatMap(Collection::stream)
+                .filter(Objects::nonNull)
+                .toArray(VirtualFile[]::new);
+        return GlobalSearchScopesCore.directoriesScope(project, /* withSubDirectories= */ true, roots);
+    }
+}
diff --git a/protobuf/protoeditor-core/test/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProviderTest.java b/protobuf/protoeditor-core/test/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProviderTest.java
new file mode 100644
index 00000000000..127e8644805
--- /dev/null
+++ b/protobuf/protoeditor-core/test/com/intellij/protobuf/lang/resolve/AdditionalLibrariesFileResolveProviderTest.java
@@ -0,0 +1,88 @@
+package com.intellij.protobuf.lang.resolve;
+
+import com.intellij.openapi.application.WriteAction;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.roots.AdditionalLibraryRootsProvider;
+import com.intellij.openapi.roots.SyntheticLibrary;
+import com.intellij.openapi.roots.ex.ProjectRootManagerEx;
+import com.intellij.openapi.util.io.FileUtil;
+import com.intellij.openapi.vfs.VfsUtil;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.openapi.vfs.VirtualFileManager;
+import com.intellij.protobuf.fixtures.PbCodeInsightFixtureTestCase;
+import com.intellij.protobuf.lang.resolve.FileResolveProvider.ChildEntry;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.UUID;
+
+/**
+ * Unit tests for {@link AdditionalLibrariesFileResolveProvider}.
+ */
+public class AdditionalLibrariesFileResolveProviderTest extends PbCodeInsightFixtureTestCase {
+
+    private File tempDir = null;
+
+    @Override
+    public void setUp() throws Exception {
+        super.setUp();
+        tempDir = FileUtil.createTempDirectory(getName(), UUID.randomUUID().toString(), false);
+        WriteAction.run(() -> ProjectRootManagerEx.getInstanceEx(getProject()).makeRootsChange(
+                () -> AdditionalLibraryRootsProvider.EP_NAME.getPoint().registerExtension(new AdditionalLibraryRootsProvider() {
+                    @NotNull
+                    @Override
+                    public Collection<SyntheticLibrary> getAdditionalProjectLibraries(@NotNull Project project) {
+                        List<VirtualFile> roots = Collections.singletonList(VfsUtil.findFile(tempDir.toPath(), true));
+                        return Collections.singletonList(SyntheticLibrary.newImmutableLibrary(roots));
+                    }
+                }, getTestRootDisposable()), false, true));
+    }
+
+    @Override
+    public void tearDown() throws Exception {
+        FileUtil.delete(tempDir);
+        super.tearDown();
+    }
+
+    public void testFindFilePrefersFirstListedPath() throws Exception {
+        FileUtil.writeToFile(new File(tempDir, "com/foo/dir/foo.proto"), "// foo");
+
+        VirtualFileManager.getInstance().syncRefresh();
+
+        FileResolveProvider resolver = new AdditionalLibrariesFileResolveProvider();
+        VirtualFile foo = resolver.findFile("com/foo/dir/foo.proto", getProject());
+
+        assertNotNull(foo);
+
+        assertEquals("// foo", VfsUtil.loadText(foo));
+    }
+
+    public void testGetChildEntries() throws Exception {
+        FileUtil.writeToFile(new File(tempDir, "com/foo/dir/foo.proto"), "// foo");
+        FileUtil.writeToFile(new File(tempDir, "com/foo/dir/bar.proto"), "// bar");
+
+        VirtualFileManager.getInstance().syncRefresh();
+
+        FileResolveProvider resolver = new AdditionalLibrariesFileResolveProvider();
+        assertContainsElements(
+                resolver.getChildEntries("", getProject()),
+                ChildEntry.directory("com"));
+        assertContainsElements(
+                resolver.getChildEntries("com", getProject()), ChildEntry.directory("foo"));
+        assertContainsElements(
+                resolver.getChildEntries("com/", getProject()), ChildEntry.directory("foo"));
+        assertContainsElements(
+                resolver.getChildEntries("com/foo", getProject()), ChildEntry.directory("dir"));
+        assertContainsElements(
+                resolver.getChildEntries("com/foo/dir", getProject()),
+                ChildEntry.file("foo.proto"),
+                ChildEntry.file("bar.proto"));
+        assertContainsElements(
+                resolver.getChildEntries("com/foo/dir/", getProject()),
+                ChildEntry.file("foo.proto"),
+                ChildEntry.file("bar.proto"));
+    }
+}
diff --git a/protobuf/resources/META-INF/plugin.xml b/protobuf/resources/META-INF/plugin.xml
index 4a7fbb40172..609e13bb678 100644
--- a/protobuf/resources/META-INF/plugin.xml
+++ b/protobuf/resources/META-INF/plugin.xml
@@ -53,6 +53,7 @@
     <!-- SettingsFileResolveProvider is listed first so that manually-configured descriptor paths always win. -->
     <fileResolveProvider id="settings" order="FIRST"
                          implementation="com.intellij.protobuf.ide.settings.SettingsFileResolveProvider"/>
+    <fileResolveProvider implementation="com.intellij.protobuf.lang.resolve.AdditionalLibrariesFileResolveProvider"/>
     <projectSettingsConfigurator id="default" order="LAST"
                                  implementation="com.intellij.protobuf.ide.settings.DefaultConfigurator"/>