diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1547,6 +1547,14 @@
                                         Group<f_clang_Group>,
                                         Flags<[CoreOption, NoXarchOption]>,
                                         HelpText<"Disable origins tracking in MemorySanitizer">;
+def fsanitize_hwaddress_experimental_aliasing
+  : Flag<["-"], "fsanitize-hwaddress-experimental-aliasing">,
+    Group<f_clang_Group>,
+    HelpText<"Enable aliasing mode in HWAddressSanitizer">;
+def fno_sanitize_hwaddress_experimental_aliasing
+  : Flag<["-"], "fno-sanitize-hwaddress-experimental-aliasing">,
+    Group<f_clang_Group>, Flags<[CoreOption, NoXarchOption]>,
+    HelpText<"Disable aliasing mode in HWAddressSanitizer">;
 defm sanitize_memory_use_after_dtor : BoolOption<"f", "sanitize-memory-use-after-dtor",
   CodeGenOpts<"SanitizeMemoryUseAfterDtor">, DefaultFalse,
   PosFlag<SetTrue, [CC1Option], "Enable">, NegFlag<SetFalse, [], "Disable">,
diff --git a/clang/include/clang/Driver/SanitizerArgs.h b/clang/include/clang/Driver/SanitizerArgs.h
--- a/clang/include/clang/Driver/SanitizerArgs.h
+++ b/clang/include/clang/Driver/SanitizerArgs.h
@@ -57,6 +57,7 @@
   // True if cross-dso CFI support if provided by the system (i.e. Android).
   bool ImplicitCfiRuntime = false;
   bool NeedsMemProfRt = false;
+  bool HwasanUseAliases = false;
 
 public:
   /// Parses the sanitizer arguments from an argument list.
@@ -69,6 +70,9 @@
   bool needsHwasanRt() const {
     return Sanitizers.has(SanitizerKind::HWAddress);
   }
+  bool needsHwasanAliasesRt() const {
+    return needsHwasanRt() && HwasanUseAliases;
+  }
   bool needsTsanRt() const { return Sanitizers.has(SanitizerKind::Thread); }
   bool needsMsanRt() const { return Sanitizers.has(SanitizerKind::Memory); }
   bool needsFuzzer() const { return Sanitizers.has(SanitizerKind::Fuzzer); }
diff --git a/clang/lib/Driver/SanitizerArgs.cpp b/clang/lib/Driver/SanitizerArgs.cpp
--- a/clang/lib/Driver/SanitizerArgs.cpp
+++ b/clang/lib/Driver/SanitizerArgs.cpp
@@ -865,6 +865,11 @@
     } else {
       HwasanAbi = "interceptor";
     }
+    if (TC.getTriple().getArch() == llvm::Triple::x86_64)
+      HwasanUseAliases = Args.hasFlag(
+          options::OPT_fsanitize_hwaddress_experimental_aliasing,
+          options::OPT_fno_sanitize_hwaddress_experimental_aliasing,
+          HwasanUseAliases);
   }
 
   if (AllAddedKinds & SanitizerKind::SafeStack) {
diff --git a/compiler-rt/test/hwasan/CMakeLists.txt b/compiler-rt/test/hwasan/CMakeLists.txt
--- a/compiler-rt/test/hwasan/CMakeLists.txt
+++ b/compiler-rt/test/hwasan/CMakeLists.txt
@@ -33,5 +33,15 @@
 add_lit_testsuite(check-hwasan "Running the HWAddressSanitizer tests"
   ${HWASAN_TESTSUITES}
   DEPENDS ${HWASAN_TEST_DEPS}
+  PARAMS "HWASAN_ENABLE_ALIASES=1"
   )
 set_target_properties(check-hwasan PROPERTIES FOLDER "Compiler-RT Misc")
+
+add_lit_testsuite(check-hwasan-lam
+  "Running the HWAddressSanitizer tests with Intel LAM"
+  ${HWASAN_TESTSUITES}
+  DEPENDS ${HWASAN_TEST_DEPS}
+  PARAMS "HWASAN_ENABLE_ALIASES=0"
+  EXCLUDE_FROM_CHECK_ALL
+  )
+set_target_properties(check-hwasan-lam PROPERTIES FOLDER "Compiler-RT Misc")
diff --git a/compiler-rt/test/hwasan/TestCases/Linux/vfork.c b/compiler-rt/test/hwasan/TestCases/Linux/vfork.c
--- a/compiler-rt/test/hwasan/TestCases/Linux/vfork.c
+++ b/compiler-rt/test/hwasan/TestCases/Linux/vfork.c
@@ -2,9 +2,7 @@
 // RUN: %clang_hwasan -O0 %s -o %t && %run %t 2>&1
 
 // REQUIRES: aarch64-target-arch || x86_64-target-arch
-
-// Aliasing mode does not support stack tagging.
-// XFAIL: x86_64
+// REQUIRES: pointer-tagging
 
 #include <assert.h>
 #include <sys/types.h>
diff --git a/compiler-rt/test/hwasan/lit.cfg.py b/compiler-rt/test/hwasan/lit.cfg.py
--- a/compiler-rt/test/hwasan/lit.cfg.py
+++ b/compiler-rt/test/hwasan/lit.cfg.py
@@ -12,6 +12,11 @@
 clang_cflags = [config.target_cflags] + config.debug_info_flags
 clang_cxxflags = config.cxx_mode_flags + clang_cflags
 clang_hwasan_common_cflags = clang_cflags + ["-fsanitize=hwaddress", "-fuse-ld=lld"]
+
+if config.target_arch == 'x86_64' and config.enable_aliases == '1':
+  clang_hwasan_common_cflags += ["-fsanitize-hwaddress-experimental-aliasing"]
+if config.enable_aliases != '1':
+  config.available_features.add('pointer-tagging')
 if config.target_arch == 'x86_64':
   # This does basically the same thing as tagged-globals on aarch64. Because
   # the x86_64 implementation is for testing purposes only there is no
diff --git a/compiler-rt/test/hwasan/lit.site.cfg.py.in b/compiler-rt/test/hwasan/lit.site.cfg.py.in
--- a/compiler-rt/test/hwasan/lit.site.cfg.py.in
+++ b/compiler-rt/test/hwasan/lit.site.cfg.py.in
@@ -6,6 +6,9 @@
 config.target_arch = "@HWASAN_TEST_TARGET_ARCH@"
 config.android_files_to_push = @HWASAN_ANDROID_FILES_TO_PUSH@
 
+# Whether to use -mlam or not.
+config.enable_aliases = lit_config.params.get("HWASAN_ENABLE_ALIASES", "@HWASAN_ENABLE_ALIASES@")
+
 # Load common config for all compiler-rt lit tests.
 lit_config.load_config(config, "@COMPILER_RT_BINARY_DIR@/test/lit.common.configured")