diff --git a/CodeGeneration/Sources/generate-swift-syntax/GenerateSwiftSyntax.swift b/CodeGeneration/Sources/generate-swift-syntax/GenerateSwiftSyntax.swift
index dd23798a666..a64b22f3d3e 100644
--- a/CodeGeneration/Sources/generate-swift-syntax/GenerateSwiftSyntax.swift
+++ b/CodeGeneration/Sources/generate-swift-syntax/GenerateSwiftSyntax.swift
@@ -139,7 +139,7 @@ struct GenerateSwiftSyntax: ParsableCommand {
 
     let modules = Set(fileSpecs.compactMap { $0.pathComponents.first })
 
-    let previouslyGeneratedFilesLock = NSLock()
+    let filesAndErrorsLock = NSLock()
     var previouslyGeneratedFiles = Set(
       modules.flatMap { (module) -> [URL] in
         let generatedDir =
@@ -163,9 +163,9 @@ struct GenerateSwiftSyntax: ParsableCommand {
           destination = destination.appendingPathComponent(component)
         }
 
-        previouslyGeneratedFilesLock.lock();
+        filesAndErrorsLock.lock();
         _ = previouslyGeneratedFiles.remove(destination)
-        previouslyGeneratedFilesLock.unlock()
+        filesAndErrorsLock.unlock()
 
         try generateFile(
           contents: fileSpec.contents,
@@ -173,13 +173,14 @@ struct GenerateSwiftSyntax: ParsableCommand {
           verbose: verbose
         )
       } catch {
+        filesAndErrorsLock.lock()
         errors.append(error)
+        filesAndErrorsLock.unlock()
       }
     }
 
-    if let firstError = errors.first {
-      // TODO: It would be nice if we could emit all errors
-      throw firstError
+    if errors.count > 0 {
+      throw ComposititeError(errors: errors)
     }
 
     for file in previouslyGeneratedFiles {
@@ -210,3 +211,13 @@ struct GenerateSwiftSyntax: ParsableCommand {
     }
   }
 }
+
+struct ComposititeError: Error, CustomStringConvertible {
+  var errors: [Error]
+  var description: String {
+    "Multiple errors emitted:\n"
+      + errors
+      .map(String.init(describing:))
+      .joined(separator: "\n")
+  }
+}