diff --git a/conf/config.py b/conf/config.py
index fbb97078..498397b9 100644
--- a/conf/config.py
+++ b/conf/config.py
@@ -173,3 +173,6 @@ class ProdConfiguration(BaseConfiguration):
 class LocalBuildConfiguration(BaseConfiguration):
     LOG_LEVEL = 'debug'
     MESSAGING = 'in_memory'
+
+    ARCH_AUTODETECT = True
+    ARCH_FALLBACK = 'x86_64'
diff --git a/module_build_service/builder/MockModuleBuilder.py b/module_build_service/builder/MockModuleBuilder.py
index 4510d944..b1b4c87e 100644
--- a/module_build_service/builder/MockModuleBuilder.py
+++ b/module_build_service/builder/MockModuleBuilder.py
@@ -28,6 +28,7 @@ import koji
 import kobo.rpmlib
 import modulemd
 import pipes
+import platform
 import re
 import threading
 
@@ -91,9 +92,21 @@ class MockModuleBuilder(GenericBuilder):
         self.tag_name = tag_name
         self.config = config
         self.groups = []
-        self.arch = "x86_64"  # TODO: We may need to change that in the future
         self.yum_conf = MockModuleBuilder.yum_config_template
 
+        # Auto-detect arch (if possible) or fallback to the configured one
+        if conf.arch_autodetect:
+            arch_detected = platform.machine()
+            if arch_detected:
+                self.arch = arch_detected
+            else:
+                log.warning("Couldn't determine machine arch. Falling back "
+                            "to configured arch.")
+                self.arch = conf.arch_fallback
+        else:
+            self.arch = conf.arch_fallback
+        log.info("Machine arch setting: {}".format(self.arch))
+
         # Create main directory for this tag
         self.tag_dir = os.path.join(self.config.mock_resultsdir, tag_name)
         if not os.path.exists(self.tag_dir):
diff --git a/module_build_service/config.py b/module_build_service/config.py
index 38c2b6cd..65314dc8 100644
--- a/module_build_service/config.py
+++ b/module_build_service/config.py
@@ -326,6 +326,14 @@ class Config(object):
             'type': bool,
             'default': True,
             'desc': 'Remove empty or otherwise useless log files.'},
+        'arch_autodetect': {
+            'type': bool,
+            'default': True,
+            'desc': 'Auto-detect machine arch when configuring builder.'},
+        'arch_fallback': {
+            'type': str,
+            'default': 'x86_64',
+            'desc': 'Fallback arch if auto-detection is off or unable to determine it.'},
         'scmurls': {
             'type': list,
             'default': [],