diff --git a/packages/flutter_tools/bin/xcode_backend.sh b/packages/flutter_tools/bin/xcode_backend.sh
index a42537c..3d6e955 100755
--- a/packages/flutter_tools/bin/xcode_backend.sh
+++ b/packages/flutter_tools/bin/xcode_backend.sh
@@ -111,6 +111,8 @@
 
   if [[ "${build_mode}" != "debug" ]]; then
     StreamOutput " ├─Building Dart code..."
+    # Transform ARCHS to comma-separated list of target architectures.
+    local archs="${ARCHS// /,}"
     RunCommand "${FLUTTER_ROOT}/bin/flutter" --suppress-analytics           \
       ${verbose_flag}                                                       \
       build aot                                                             \
@@ -118,6 +120,7 @@
       --target-platform=ios                                                 \
       --target="${target_path}"                                             \
       --${build_mode}                                                       \
+      --ios-arch="${archs}"                                                 \
       ${local_engine_flag}                                                  \
       ${preview_dart_2_flag}
 
diff --git a/packages/flutter_tools/lib/src/base/build.dart b/packages/flutter_tools/lib/src/base/build.dart
index be6f94c..d14cfa6 100644
--- a/packages/flutter_tools/lib/src/base/build.dart
+++ b/packages/flutter_tools/lib/src/base/build.dart
@@ -40,6 +40,7 @@
     @required SnapshotType snapshotType,
     @required String packagesPath,
     @required String depfilePath,
+    IOSArch iosArch,
     Iterable<String> additionalArgs: const <String>[],
   }) {
     final List<String> args = <String>[
@@ -56,8 +57,8 @@
     // code. /usr/bin/arch can be used to run binaries with the specified
     // architecture.
     if (snapshotType.platform == TargetPlatform.ios) {
-      // TODO(cbracken): for the moment, always generate only arm64 code.
-      return runCommandAndStreamOutput(<String>['/usr/bin/arch', '-x86_64', snapshotterPath]..addAll(args));
+      final String hostArch = iosArch == IOSArch.armv7 ? '-i386' : '-x86_64';
+      return runCommandAndStreamOutput(<String>['/usr/bin/arch', hostArch, snapshotterPath]..addAll(args));
     }
     return runCommandAndStreamOutput(<String>[snapshotterPath]..addAll(args));
   }
@@ -137,12 +138,15 @@
     @required String outputPath,
     @required bool previewDart2,
     @required bool preferSharedLibrary,
+    IOSArch iosArch,
     List<String> extraGenSnapshotOptions: const <String>[],
   }) async {
     if (!_isValidAotPlatform(platform, buildMode)) {
       printError('${getNameForTargetPlatform(platform)} does not support AOT compilation.');
       return -1;
     }
+    // TODO(cbracken): replace IOSArch with TargetPlatform.ios_{armv7,arm64}.
+    assert(platform != TargetPlatform.ios || iosArch != null);
 
     final bool compileToSharedLibrary = preferSharedLibrary && androidSdk.ndkCompiler != null;
     if (preferSharedLibrary && !compileToSharedLibrary) {
@@ -215,7 +219,7 @@
       ]);
     }
 
-    if (platform == TargetPlatform.android_arm) {
+    if (platform == TargetPlatform.android_arm || iosArch == IOSArch.armv7) {
       // Not supported by the Pixel in 32-bit mode.
       genSnapshotArgs.add('--no-use-integer-division');
     }
@@ -253,6 +257,7 @@
       packagesPath: packageMap.packagesPath,
       depfilePath: depfilePath,
       additionalArgs: genSnapshotArgs,
+      iosArch: iosArch,
     );
     if (genSnapshotExitCode != 0) {
       printError('Dart snapshot generator failed with exit code $genSnapshotExitCode');
@@ -266,7 +271,7 @@
     // On iOS, we use Xcode to compile the snapshot into a dynamic library that the
     // end-developer can link into their app.
     if (platform == TargetPlatform.ios) {
-      final RunResult result = await _buildIosFramework(assemblyPath: assembly, outputPath: outputDir.path);
+      final RunResult result = await _buildIosFramework(iosArch: iosArch, assemblyPath: assembly, outputPath: outputDir.path);
       if (result.exitCode != 0)
         return result.exitCode;
     } else if (compileToSharedLibrary) {
@@ -283,11 +288,13 @@
   /// Builds an iOS framework at [outputPath]/App.framework from the assembly
   /// source at [assemblyPath].
   Future<RunResult> _buildIosFramework({
+    @required IOSArch iosArch,
     @required String assemblyPath,
     @required String outputPath,
   }) async {
-    printStatus('Building App.framework...');
-    const List<String> commonBuildOptions = const <String>['-arch', 'arm64', '-miphoneos-version-min=8.0'];
+    final String targetArch = iosArch == IOSArch.armv7 ? 'armv7' : 'arm64';
+    printStatus('Building App.framework for $targetArch...');
+    final List<String> commonBuildOptions = <String>['-arch', targetArch, '-miphoneos-version-min=8.0'];
 
     final String assemblyO = fs.path.join(outputPath, 'snapshot_assembly.o');
     final RunResult compileResult = await xcode.cc(commonBuildOptions.toList()..addAll(<String>['-c', assemblyPath, '-o', assemblyO]));
diff --git a/packages/flutter_tools/lib/src/build_info.dart b/packages/flutter_tools/lib/src/build_info.dart
index 82e7dea..2472b9d 100644
--- a/packages/flutter_tools/lib/src/build_info.dart
+++ b/packages/flutter_tools/lib/src/build_info.dart
@@ -160,6 +160,41 @@
   tester,
 }
 
+/// iOS target device architecture.
+//
+// TODO(cbracken): split TargetPlatform.ios into ios_armv7, ios_arm64.
+enum IOSArch {
+  armv7,
+  arm64,
+}
+
+/// The default set of iOS device architectures to build for.
+const List<IOSArch> defaultIOSArchs = const <IOSArch>[
+  IOSArch.arm64,
+];
+
+String getNameForIOSArch(IOSArch arch) {
+  switch (arch) {
+    case IOSArch.armv7:
+      return 'armv7';
+    case IOSArch.arm64:
+      return 'arm64';
+  }
+  assert(false);
+  return null;
+}
+
+IOSArch getIOSArchForName(String arch) {
+  switch (arch) {
+    case 'armv7':
+      return IOSArch.armv7;
+    case 'arm64':
+      return IOSArch.arm64;
+  }
+  assert(false);
+  return null;
+}
+
 String getNameForTargetPlatform(TargetPlatform platform) {
   switch (platform) {
     case TargetPlatform.android_arm:
diff --git a/packages/flutter_tools/lib/src/commands/build_aot.dart b/packages/flutter_tools/lib/src/commands/build_aot.dart
index ee36b69..d67c2a6 100644
--- a/packages/flutter_tools/lib/src/commands/build_aot.dart
+++ b/packages/flutter_tools/lib/src/commands/build_aot.dart
@@ -8,6 +8,7 @@
 import '../base/common.dart';
 import '../base/file_system.dart';
 import '../base/logger.dart';
+import '../base/process.dart';
 import '../build_info.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
@@ -32,6 +33,12 @@
         hide: !verboseHelp,
         help: 'Preview Dart 2.0 functionality.',
       )
+      ..addMultiOption('ios-arch',
+        splitCommas: true,
+        defaultsTo: defaultIOSArchs.map(getNameForIOSArch),
+        allowed: IOSArch.values.map(getNameForIOSArch),
+        help: 'iOS architectures to build',
+      )
       ..addMultiOption(FlutterOptions.kExtraFrontEndOptions,
         splitCommas: true,
         hide: true,
@@ -90,18 +97,57 @@
       }
 
       // Build AOT snapshot.
-      final int snapshotExitCode = await snapshotter.build(
-        platform: platform,
-        buildMode: buildMode,
-        mainPath: mainPath,
-        packagesPath: PackageMap.globalPackagesPath,
-        outputPath: outputPath,
-        previewDart2: previewDart2,
-        preferSharedLibrary: argResults['prefer-shared-library'],
-        extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
-      );
-      if (snapshotExitCode != 0) {
-        printError('Snapshotting exited with non-zero exit code: $snapshotExitCode');
+      if (platform == TargetPlatform.ios) {
+        // Determine which iOS architectures to build for.
+        final Iterable<IOSArch> buildArchs = argResults['ios-arch'].map(getIOSArchForName);
+        final Map<IOSArch, String> iosBuilds = <IOSArch, String>{};
+        for (IOSArch arch in buildArchs)
+          iosBuilds[arch] = fs.path.join(outputPath, getNameForIOSArch(arch));
+
+        // Generate AOT snapshot and compile to arch-specific App.framework.
+        final Map<IOSArch, Future<int>> exitCodes = <IOSArch, Future<int>>{};
+        iosBuilds.forEach((IOSArch iosArch, String outputPath) {
+          exitCodes[iosArch] = snapshotter.build(
+            platform: platform,
+            iosArch: iosArch,
+            buildMode: buildMode,
+            mainPath: mainPath,
+            packagesPath: PackageMap.globalPackagesPath,
+            outputPath: outputPath,
+            previewDart2: previewDart2,
+            preferSharedLibrary: false,
+            extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
+          ).then((int buildExitCode) {
+            if (buildExitCode != 0)
+              printError('Snapshotting ($iosArch) exited with non-zero exit code: $buildExitCode');
+            return buildExitCode;
+          });
+        });
+
+        // Merge arch-specific App.frameworks into a multi-arch App.framework.
+        if ((await Future.wait(exitCodes.values)).every((int buildExitCode) => buildExitCode == 0)) {
+          final Iterable<String> dylibs = iosBuilds.values.map((String outputDir) => fs.path.join(outputDir, 'App.framework', 'App'));
+          fs.directory(fs.path.join(outputPath, 'App.framework'))..createSync();
+          await runCheckedAsync(<String>['lipo']
+            ..addAll(dylibs)
+            ..addAll(<String>['-create', '-output', fs.path.join(outputPath, 'App.framework', 'App')]),
+          );
+        }
+      } else {
+        // Android AOT snapshot.
+        final int snapshotExitCode = await snapshotter.build(
+          platform: platform,
+          buildMode: buildMode,
+          mainPath: mainPath,
+          packagesPath: PackageMap.globalPackagesPath,
+          outputPath: outputPath,
+          previewDart2: previewDart2,
+          preferSharedLibrary: argResults['prefer-shared-library'],
+          extraGenSnapshotOptions: argResults[FlutterOptions.kExtraGenSnapshotOptions],
+        );
+        if (snapshotExitCode != 0) {
+          printError('Snapshotting exited with non-zero exit code: $snapshotExitCode');
+        }
       }
     } on String catch (error) {
       // Catch the String exceptions thrown from the `runCheckedSync` methods below.
diff --git a/packages/flutter_tools/lib/src/ios/mac.dart b/packages/flutter_tools/lib/src/ios/mac.dart
index 08333f1..2248932 100644
--- a/packages/flutter_tools/lib/src/ios/mac.dart
+++ b/packages/flutter_tools/lib/src/ios/mac.dart
@@ -325,7 +325,6 @@
     'xcrun',
     'xcodebuild',
     '-configuration', configuration,
-    'ONLY_ACTIVE_ARCH=YES',
   ];
 
   if (logger.isVerbose) {
@@ -358,7 +357,7 @@
   }
 
   if (buildForDevice) {
-    buildCommands.addAll(<String>['-sdk', 'iphoneos', '-arch', 'arm64']);
+    buildCommands.addAll(<String>['-sdk', 'iphoneos']);
   } else {
     buildCommands.addAll(<String>['-sdk', 'iphonesimulator', '-arch', 'x86_64']);
   }
diff --git a/packages/flutter_tools/test/base/build_test.dart b/packages/flutter_tools/test/base/build_test.dart
index a3a9a0e..39244a2 100644
--- a/packages/flutter_tools/test/base/build_test.dart
+++ b/packages/flutter_tools/test/base/build_test.dart
@@ -52,6 +52,7 @@
     SnapshotType snapshotType,
     String packagesPath,
     String depfilePath,
+    IOSArch iosArch,
     Iterable<String> additionalArgs,
   }) async {
     _callCount += 1;
@@ -361,6 +362,7 @@
         outputPath: outputPath,
         preferSharedLibrary: false,
         previewDart2: true,
+        iosArch: IOSArch.arm64,
       );
 
       expect(genSnapshotExitCode, 0);
@@ -407,6 +409,7 @@
         outputPath: outputPath,
         preferSharedLibrary: false,
         previewDart2: true,
+        iosArch: IOSArch.arm64,
       );
 
       expect(genSnapshotExitCode, 0);