diff --git a/master/master.cfg b/master/master.cfg
index e6783e20..a10cd082 100644
--- a/master/master.cfg
+++ b/master/master.cfg
@@ -158,7 +158,7 @@ c['workers'] = [Worker(n,
                        properties={'WORKER_BUILD_PARALLELISM': cfg.j}) for n, cfg in _WORKERS]
 
 _SANITIZERS = [
-    # 'asan',  # TODO: weird error about precompiled header file
+    'asan',
     'fuzzer',  # this isn't *technically* a sanitizer, but is close enough that it's a good fit
 ]
 
@@ -715,7 +715,7 @@ def get_llvm_cmake_definitions(builder_type):
         'LLVM_ENABLE_OCAMLDOC': 'OFF',
         'LLVM_ENABLE_RTTI': 'ON',
         'LLVM_ENABLE_TERMINFO': 'OFF',
-        'LLVM_ENABLE_WARNINGS': 'ON',  # silence them, it's not like we're gonna fix them
+        'LLVM_ENABLE_WARNINGS': 'OFF',  # silence them, it's not like we're gonna fix them
         'LLVM_ENABLE_ZLIB': 'ON',
         'LLVM_ENABLE_ZSTD': 'OFF',
         'LLVM_INCLUDE_BENCHMARKS': 'OFF',
@@ -814,6 +814,8 @@ def add_env_setup_step(factory, builder_type, enable_ccache=False):
         'CC': cc,
         'CXX': cxx,
         'LD': ld,
+        # Only needed for ASAN builds, but easier to just always specify
+        'ASAN_SYMBOLIZER_PATH': get_llvm_install_path(builder_type, 'bin/llvm-symbolizer')
     }
 
     # TODO: HALIDE_NODE_JS_PATH is only necessary until EMSDK updates their built-in version of Node
@@ -966,14 +968,19 @@ def add_halide_cmake_build_steps(factory, builder_type):
                           definitions=get_halide_cmake_definitions(builder_type),
                           options=get_halide_cmake_options(builder_type, build_dir)))
 
-    factory.addStep(
-        ShellCommand(name='Build Halide',
-                     description='Build Halide',
-                     locks=[performance_lock.access('counting')],
-                     haltOnFailure=True,
-                     workdir=build_dir,
-                     env=Property('env'),
-                     command=get_cmake_build_command(builder_type, build_dir, targets=['all', 'install'])))
+    # Don't do this initial build:
+    # We always follow this with a call to add_halide_cmake_test_steps(),
+    # which will reconfigure CMake and rebuild. For most targets, the extra
+    # build is close to a no-op (building for `host` again), but for Sanitizer
+    # builds, it's just wasted effort.
+    # factory.addStep(
+    #     ShellCommand(name='Build Halide',
+    #                  description='Build Halide',
+    #                  locks=[performance_lock.access('counting')],
+    #                  haltOnFailure=True,
+    #                  workdir=build_dir,
+    #                  env=Property('env'),
+    #                  command=get_cmake_build_command(builder_type, build_dir, targets=['all', 'install'])))
 
 
 def add_halide_cmake_package_steps(factory, builder_type):