diff --git a/GitUp/Application/DocumentController.m b/GitUp/Application/DocumentController.m
index 10d21c15..7578f4c4 100644
--- a/GitUp/Application/DocumentController.m
+++ b/GitUp/Application/DocumentController.m
@@ -31,6 +31,18 @@ - (void)beginOpenPanel:(NSOpenPanel*)openPanel forTypes:(NSArray*)inTypes comple
   [super beginOpenPanel:openPanel forTypes:inTypes completionHandler:completionHandler];
 }
 
+- (void)openDocumentWithContentsOfURL:(NSURL *)url display:(BOOL)displayDocument completionHandler:(void (^)(NSDocument *_Nullable, BOOL, NSError *_Nullable))completionHandler {
+  NSError *error;
+  NSURL *repositoryURL = [GCRepository repositoryURLContainingURL:url error:&error];
+
+  if (repositoryURL) {
+    [super openDocumentWithContentsOfURL:repositoryURL display:displayDocument completionHandler:completionHandler];
+  } else {
+    // Document already handles the URL not being a repository so just reuse that failure handling.
+    [super openDocumentWithContentsOfURL:url display:displayDocument completionHandler:completionHandler];
+  }
+}
+
 - (NSError*)willPresentError:(NSError*)error {
   NSError* underlyingError = [error.userInfo objectForKey:NSUnderlyingErrorKey];
   if ([underlyingError.domain isEqualToString:GCErrorDomain]) {
diff --git a/GitUpKit/Core/GCRepository-Tests.m b/GitUpKit/Core/GCRepository-Tests.m
index 76a709b1..e2b823b1 100644
--- a/GitUpKit/Core/GCRepository-Tests.m
+++ b/GitUpKit/Core/GCRepository-Tests.m
@@ -55,6 +55,34 @@ - (void)testOpen {
   XCTAssertTrue([[NSFileManager defaultManager] removeItemAtPath:path error:NULL]);
 }
 
+- (void)testRepositoryURLContainingURL {
+  NSString* parentPath = [NSTemporaryDirectory() stringByAppendingPathComponent:[[NSProcessInfo processInfo] globallyUniqueString]];
+  XCTAssertTrue([[NSFileManager defaultManager] createDirectoryAtPath:parentPath withIntermediateDirectories:NO attributes:nil error:NULL]);
+
+  NSString* repositoryPath = [parentPath stringByAppendingPathComponent:@"repository"];
+  GCRepository* repository = [self createLocalRepositoryAtPath:repositoryPath bare:NO];
+  NSURL* expectedURL = [NSURL fileURLWithPath:repository.workingDirectoryPath];
+
+  NSError* error = nil;
+  NSURL* sameDirectoryURL = [GCRepository repositoryURLContainingURL:expectedURL error:&error];
+  XCTAssertEqualObjects(sameDirectoryURL.path.stringByStandardizingPath, expectedURL.path.stringByStandardizingPath);
+  XCTAssertNil(error);
+
+  NSString* subdirectoryPath = [repository.workingDirectoryPath stringByAppendingPathComponent:@"subdirectory"];
+  XCTAssertTrue([[NSFileManager defaultManager] createDirectoryAtPath:subdirectoryPath withIntermediateDirectories:NO attributes:nil error:NULL]);
+  error = nil;
+  NSURL* subdirectoryURL = [GCRepository repositoryURLContainingURL:[NSURL fileURLWithPath:subdirectoryPath] error:&error];
+  XCTAssertEqualObjects(subdirectoryURL.path.stringByStandardizingPath, expectedURL.path.stringByStandardizingPath);
+  XCTAssertNil(error);
+
+  error = nil;
+  XCTAssertNil([GCRepository repositoryURLContainingURL:[NSURL fileURLWithPath:parentPath] error:&error]);
+  XCTAssertEqual(error.code, kGCErrorCode_NotFound);
+
+  [self destroyLocalRepository:repository];
+  XCTAssertTrue([[NSFileManager defaultManager] removeItemAtPath:parentPath error:NULL]);
+}
+
 @end
 
 @implementation GCEmptyRepositoryTests (GCRepository)
diff --git a/GitUpKit/Core/GCRepository.h b/GitUpKit/Core/GCRepository.h
index 244ed7e9..cf7240f0 100644
--- a/GitUpKit/Core/GCRepository.h
+++ b/GitUpKit/Core/GCRepository.h
@@ -52,6 +52,8 @@ typedef NS_ENUM(NSUInteger, GCFileMode) {
 @end
 
 @interface GCRepository : NSObject
+/// Walks up the file system to find the repository the given URL is contained in. Returns nil and sets the error if no repository is found.
++ (NSURL *)repositoryURLContainingURL:(NSURL *)url error:(NSError **)error;
 @property(nonatomic, weak) id<GCRepositoryDelegate> delegate;
 @property(nonatomic, readonly) NSString* repositoryPath;
 @property(nonatomic, readonly) NSString* workingDirectoryPath;  // nil for a bare repository
diff --git a/GitUpKit/Core/GCRepository.m b/GitUpKit/Core/GCRepository.m
index 79e6ac2f..43f9ac8a 100644
--- a/GitUpKit/Core/GCRepository.m
+++ b/GitUpKit/Core/GCRepository.m
@@ -133,6 +133,35 @@ + (void)load {
 #endif
 }
 
++ (NSURL *)repositoryURLContainingURL:(NSURL *)url error:(NSError *__autoreleasing *)error {
+  NSParameterAssert(url.isFileURL);
+
+  git_buf repoBuffer = {0};
+
+  int result = git_repository_discover(&repoBuffer, GCGitPathFromFileSystemPath(url.path), false, NULL);
+  if (result == GIT_OK) {
+    NSString* repoPath = [[NSString alloc] initWithBytes:repoBuffer.ptr length:repoBuffer.size encoding:NSUTF8StringEncoding];
+    NSURL* repoURL = [NSURL fileURLWithPath:repoPath];
+    git_buf_dispose(&repoBuffer);
+
+    // Need to trim the .git from the path, otherwise it works but the document title is .git.
+
+    if ([repoURL.lastPathComponent isEqualToString:@".git"]) {
+      return [repoURL URLByDeletingLastPathComponent];
+    } else {
+      XLOG_WARNING(@"Discovered repository URL not ending in .git: “%@”", repoURL.path);
+      return repoURL;
+    }
+  }
+
+  if (result == GIT_ENOTFOUND) {
+    GC_SET_ERROR(kGCErrorCode_NotFound, @"No repository found");
+  } else {
+    GC_SET_GENERIC_ERROR(@"Error %d", result);
+  }
+  return nil;
+}
+
 - (instancetype)initWithRepository:(git_repository*)repository error:(NSError**)error {
   if ((self = [super init])) {
     _private = repository;