diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 394a94cb663..c0363788c9e 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -147,6 +147,12 @@ namespace ts {
             category: Diagnostics.Basic_Options,
             description: Diagnostics.Enable_incremental_compilation,
         },
+        {
+            name: "locale",
+            type: "string",
+            category: Diagnostics.Advanced_Options,
+            description: Diagnostics.The_locale_used_when_displaying_messages_to_the_user_e_g_en_us
+        },
     ];
 
     /* @internal */
@@ -698,12 +704,6 @@ namespace ts {
             category: Diagnostics.Advanced_Options,
             description: Diagnostics.Emit_a_UTF_8_Byte_Order_Mark_BOM_in_the_beginning_of_output_files
         },
-        {
-            name: "locale",
-            type: "string",
-            category: Diagnostics.Advanced_Options,
-            description: Diagnostics.The_locale_used_when_displaying_messages_to_the_user_e_g_en_us
-        },
         {
             name: "newLine",
             type: createMapFromTemplate({
@@ -1171,7 +1171,7 @@ namespace ts {
     export interface ParsedBuildCommand {
         buildOptions: BuildOptions;
         projects: string[];
-        errors: ReadonlyArray<Diagnostic>;
+        errors: Diagnostic[];
     }
 
     /*@internal*/
diff --git a/src/compiler/tsbuild.ts b/src/compiler/tsbuild.ts
index 94718a1b368..4602c0793be 100644
--- a/src/compiler/tsbuild.ts
+++ b/src/compiler/tsbuild.ts
@@ -172,6 +172,7 @@ namespace ts {
         traceResolution?: boolean;
         /* @internal */ diagnostics?: boolean;
         /* @internal */ extendedDiagnostics?: boolean;
+        /* @internal */ locale?: string;
 
         [option: string]: CompilerOptionsValue | undefined;
     }
diff --git a/src/testRunner/unittests/config/commandLineParsing.ts b/src/testRunner/unittests/config/commandLineParsing.ts
index 3c033d658ef..3d1001c7daf 100644
--- a/src/testRunner/unittests/config/commandLineParsing.ts
+++ b/src/testRunner/unittests/config/commandLineParsing.ts
@@ -486,6 +486,16 @@ namespace ts {
                 });
         });
 
+        it("parse build with --locale en-us", () => {
+            // --lib es6 0.ts
+            assertParseResult(["--locale", "en-us", "src"],
+                {
+                    errors: [],
+                    projects: ["src"],
+                    buildOptions: { locale: "en-us" }
+                });
+        });
+
         it("parse build with --tsBuildInfoFile", () => {
             // --lib es6 0.ts
             assertParseResult(["--tsBuildInfoFile", "build.tsbuildinfo", "tests"],
diff --git a/src/tsc/tsc.ts b/src/tsc/tsc.ts
index 6a340109238..d27c1aace4e 100644
--- a/src/tsc/tsc.ts
+++ b/src/tsc/tsc.ts
@@ -186,6 +186,10 @@ namespace ts {
         // Update to pretty if host supports it
         updateReportDiagnostic(buildOptions);
 
+        if (buildOptions.locale) {
+            validateLocaleAndSetLanguage(buildOptions.locale, sys, errors);
+        }
+
         if (errors.length > 0) {
             errors.forEach(reportDiagnostic);
             return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);