diff --git a/BUILD.gn b/BUILD.gn
index 4d91cbfce27..f74aea74f36 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -867,9 +867,6 @@ source_set("v8_base") {
     "src/compiler/value-numbering-reducer.h",
     "src/compiler/verifier.cc",
     "src/compiler/verifier.h",
-    "src/compiler/wasm-compiler.cc",
-    "src/compiler/wasm-compiler.h",
-    "src/compiler/wasm-linkage.cc",
     "src/compiler/zone-pool.cc",
     "src/compiler/zone-pool.h",
     "src/compiler.cc",
@@ -1285,24 +1282,6 @@ source_set("v8_base") {
     "src/version.h",
     "src/vm-state-inl.h",
     "src/vm-state.h",
-    "src/wasm/asm-wasm-builder.cc",
-    "src/wasm/asm-wasm-builder.h",
-    "src/wasm/ast-decoder.cc",
-    "src/wasm/ast-decoder.h",
-    "src/wasm/decoder.h",
-    "src/wasm/encoder.cc",
-    "src/wasm/encoder.h",
-    "src/wasm/module-decoder.cc",
-    "src/wasm/module-decoder.h",
-    "src/wasm/wasm-js.cc",
-    "src/wasm/wasm-js.h",
-    "src/wasm/wasm-macro-gen.h",
-    "src/wasm/wasm-module.cc",
-    "src/wasm/wasm-module.h",
-    "src/wasm/wasm-opcodes.cc",
-    "src/wasm/wasm-opcodes.h",
-    "src/wasm/wasm-result.cc",
-    "src/wasm/wasm-result.h",
     "src/zone.cc",
     "src/zone.h",
     "src/zone-allocator.h",
diff --git a/Makefile b/Makefile
index c2caf40f4dc..28c1af2e07f 100644
--- a/Makefile
+++ b/Makefile
@@ -220,6 +220,12 @@ ifeq ($(arm_test_noprobe), on)
   GYPFLAGS += -Darm_test_noprobe=on
 endif
 
+# Optionally enable wasm prototype.
+# Assume you've placed a link to v8-native-prototype in third_party/wasm.
+ifeq ($(wasm), on)
+  GYPFLAGS += -Dv8_wasm=1
+endif
+
 # ----------------- available targets: --------------------
 # - "grokdump": rebuilds heap constants lists used by grokdump
 # - any arch listed in ARCHES (see below)
diff --git a/build/features.gypi b/build/features.gypi
index f82a59f0f82..1ee3e569a76 100644
--- a/build/features.gypi
+++ b/build/features.gypi
@@ -67,6 +67,9 @@
     # Set to 1 to enable DCHECKs in release builds.
     'dcheck_always_on%': 0,
 
+    # Set to 1 to enable building with wasm prototype.
+    'v8_wasm%': 0,
+
     # Enable/disable JavaScript API accessors.
     'v8_js_accessors%': 0,
   },
@@ -108,6 +111,9 @@
       ['dcheck_always_on!=0', {
         'defines': ['DEBUG',],
       }],
+      ['v8_wasm!=0', {
+        'defines': ['V8_WASM',],
+      }],
     ],  # conditions
     'configurations': {
       'DebugBaseCommon': {
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 72d7f994b11..4409d935229 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -16,7 +16,11 @@
 #include "src/isolate-inl.h"
 #include "src/snapshot/natives.h"
 #include "src/snapshot/snapshot.h"
+#include "third_party/fdlibm/fdlibm.h"
+
+#if defined(V8_WASM)
 #include "src/wasm/wasm-js.h"
+#endif
 
 namespace v8 {
 namespace internal {
@@ -2851,9 +2855,11 @@ bool Genesis::InstallSpecialObjects(Handle<Context> native_context) {
     JSObject::AddProperty(global, debug_string, global_proxy, DONT_ENUM);
   }
 
+#if defined(V8_WASM)
   if (FLAG_expose_wasm) {
     WasmJs::Install(isolate, global);
   }
+#endif
 
   return true;
 }
diff --git a/src/d8.gyp b/src/d8.gyp
index f249a78856a..2e4a6e0cc5c 100644
--- a/src/d8.gyp
+++ b/src/d8.gyp
@@ -101,6 +101,9 @@
             '<(icu_gyp_path):icudata',
           ],
         }],
+        ['v8_wasm!=0', {
+          'include_dirs': ['../third_party/wasm'],
+        }],
       ],
     },
     {
diff --git a/test/cctest/cctest.gyp b/test/cctest/cctest.gyp
index 5d0bbfe004e..4e4674e6cfc 100644
--- a/test/cctest/cctest.gyp
+++ b/test/cctest/cctest.gyp
@@ -183,9 +183,6 @@
         'test-weakmaps.cc',
         'test-weaksets.cc',
         'trace-extension.cc',
-        'wasm/test-run-wasm.cc',
-        'wasm/test-run-wasm-module.cc',
-        'wasm/test-signatures.h',
       ],
       'conditions': [
         ['v8_target_arch=="ia32"', {
@@ -302,6 +299,13 @@
         }, {
           'dependencies': ['../../tools/gyp/v8.gyp:v8'],
         }],
+        ['v8_wasm!=0', {
+          'sources': [
+            'wasm/test-run-wasm.cc',
+            'wasm/test-run-wasm-module.cc',
+            'wasm/test-signatures.h',
+          ],
+        }],
       ],
     },
     {
diff --git a/test/mjsunit/mjsunit.status b/test/mjsunit/mjsunit.status
index 598726da6b7..f32b242cb83 100644
--- a/test/mjsunit/mjsunit.status
+++ b/test/mjsunit/mjsunit.status
@@ -166,6 +166,9 @@
   # issue 4078:
   'allocation-site-info': [PASS, NO_VARIANTS],
 
+  # Native WASM is not yet enabled by default.
+  'wasm/*': [SKIP],
+
   ##############################################################################
   # Too slow in debug mode with --stress-opt mode.
   'compiler/regress-stacktrace-methods': [PASS, ['mode == debug', SKIP]],
@@ -736,28 +739,6 @@
   'regress/regress-1132': [SKIP],
 }],  # 'arch == ppc and simulator_run == True'
 
-
-# TODO(bradnelson): Figure out why this fails for arm.
-['arch == arm', {
-  'wasm/asm-wasm': [SKIP],
-}],
-
-# TODO(bradnelson): Figure out why this crashes under asan.
-['asan == True', {
-  'wasm/asm-wasm': [SKIP],
-}],
-
-# TODO(titzer): Figure out why parameter passing on 32-bit is broken.
-['arch != x64', {
-  'wasm/params': [SKIP],
-}],
-
-# TODO(titzer): Figure out why arm64 is broken for wasm.
-['arch == arm64', {
-  'wasm/*': [SKIP],
-}],
-
-
 ['ignition == True', {
   'asm/*': [SKIP],
   'compiler/*': [SKIP],
@@ -769,7 +750,6 @@
   'harmony/*': [SKIP],
   'regress/debug*': [SKIP],
   'regress/regress-debug*': [SKIP],
-  'wasm/*': [SKIP],
 
   'allocation-folding': [SKIP],
   'api-call-after-bypassed-exception': [SKIP],
diff --git a/test/unittests/unittests.gyp b/test/unittests/unittests.gyp
index 2c768a042b7..a905b7dace7 100644
--- a/test/unittests/unittests.gyp
+++ b/test/unittests/unittests.gyp
@@ -110,10 +110,6 @@
         'runtime/runtime-interpreter-unittest.cc',
         'test-utils.h',
         'test-utils.cc',
-        'wasm/ast-decoder-unittest.cc',
-        'wasm/encoder-unittest.cc',
-        'wasm/module-decoder-unittest.cc',
-        'wasm/wasm-macro-gen-unittest.cc',
       ],
       'conditions': [
         ['v8_target_arch=="arm"', {
@@ -173,6 +169,14 @@
             ],
           },
         }],
+        ['v8_wasm!=0', {
+          'sources': [
+            'wasm/ast-decoder-unittest.cc',
+            'wasm/encoder-unittest.cc',
+            'wasm/module-decoder-unittest.cc',
+            'wasm/wasm-macro-gen-unittest.cc',
+          ],
+        }],
       ],
     },
   ],
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index b040ba41214..d23c9bda1cc 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -646,9 +646,6 @@
         '../../src/compiler/value-numbering-reducer.h',
         '../../src/compiler/verifier.cc',
         '../../src/compiler/verifier.h',
-        '../../src/compiler/wasm-compiler.cc',
-        '../../src/compiler/wasm-compiler.h',
-        '../../src/compiler/wasm-linkage.cc',
         '../../src/compiler/zone-pool.cc',
         '../../src/compiler/zone-pool.h',
         '../../src/compiler.cc',
@@ -1069,24 +1066,6 @@
         '../../src/version.h',
         '../../src/vm-state-inl.h',
         '../../src/vm-state.h',
-        '../../src/wasm/asm-wasm-builder.cc',
-        '../../src/wasm/asm-wasm-builder.h',
-        '../../src/wasm/ast-decoder.cc',
-        '../../src/wasm/ast-decoder.h',
-        '../../src/wasm/decoder.h',
-        '../../src/wasm/encoder.cc',
-        '../../src/wasm/encoder.h',
-        '../../src/wasm/module-decoder.cc',
-        '../../src/wasm/module-decoder.h',
-        '../../src/wasm/wasm-js.cc',
-        '../../src/wasm/wasm-js.h',
-        '../../src/wasm/wasm-macro-gen.h',
-        '../../src/wasm/wasm-module.cc',
-        '../../src/wasm/wasm-module.h',
-        '../../src/wasm/wasm-opcodes.cc',
-        '../../src/wasm/wasm-opcodes.h',
-        '../../src/wasm/wasm-result.cc',
-        '../../src/wasm/wasm-result.h',
         '../../src/zone.cc',
         '../../src/zone.h',
         '../../src/zone-allocator.h',
@@ -1500,6 +1479,31 @@
             }],
           ],
         }],
+        ['v8_wasm!=0', {
+          'sources': [
+            '../../src/compiler/wasm-compiler.cc',
+            '../../src/compiler/wasm-compiler.h',
+            '../../src/compiler/wasm-linkage.cc',
+            '../../src/wasm/asm-wasm-builder.cc',
+            '../../src/wasm/asm-wasm-builder.h',
+            '../../src/wasm/ast-decoder.cc',
+            '../../src/wasm/ast-decoder.h',
+            '../../src/wasm/decoder.h',
+            '../../src/wasm/encoder.cc',
+            '../../src/wasm/encoder.h',
+            '../../src/wasm/module-decoder.cc',
+            '../../src/wasm/module-decoder.h',
+            '../../src/wasm/wasm-js.cc',
+            '../../src/wasm/wasm-js.h',
+            '../../src/wasm/wasm-macro-gen.h',
+            '../../src/wasm/wasm-module.cc',
+            '../../src/wasm/wasm-module.h',
+            '../../src/wasm/wasm-opcodes.cc',
+            '../../src/wasm/wasm-opcodes.h',
+            '../../src/wasm/wasm-result.cc',
+            '../../src/wasm/wasm-result.h',
+          ],
+        }],
       ],
     },
     {