diff --git a/src/wasm2obj.rs b/src/wasm2obj.rs
index 754efdc174..bc99441bd8 100644
--- a/src/wasm2obj.rs
+++ b/src/wasm2obj.rs
@@ -31,6 +31,7 @@
 
 use cranelift_codegen::isa;
 use cranelift_codegen::settings;
+use cranelift_codegen::settings::Configurable;
 use cranelift_native;
 use docopt::Docopt;
 use faerie::Artifact;
@@ -62,7 +63,7 @@ The translation is dependent on the environment chosen.
 The default is a dummy environment that produces placeholder values.
 
 Usage:
-    wasm2obj [--target TARGET] [-cdg] <file> -o <output>
+    wasm2obj [--target TARGET] [-cdg] [--enable-simd] <file> -o <output>
     wasm2obj --help | --version
 
 Options:
@@ -71,6 +72,7 @@ Options:
     --target <TARGET>   build for the target triple; default is the host machine
     -g                  generate debug information
     -c, --cache         enable caching system
+    --enable-simd       enable proposed SIMD instructions
     --version           print the Cranelift version
     -d, --debug         enable debug output on stderr/stdout
 ";
@@ -83,6 +85,7 @@ struct Args {
     flag_g: bool,
     flag_debug: bool,
     flag_cache: bool,
+    flag_enable_simd: bool,
 }
 
 fn read_wasm_file(path: PathBuf) -> Result<Vec<u8>, io::Error> {
@@ -116,6 +119,7 @@ fn main() {
         &args.arg_target,
         &args.arg_output,
         args.flag_g,
+        args.flag_enable_simd,
     ) {
         Ok(()) => {}
         Err(message) => {
@@ -130,6 +134,7 @@ fn handle_module(
     target: &Option<String>,
     output: &str,
     generate_debug_info: bool,
+    enable_simd: bool,
 ) -> Result<(), String> {
     let data = match read_wasm_file(path) {
         Ok(data) => data,
@@ -152,7 +157,10 @@ fn handle_module(
             panic!("host machine is not a supported target");
         }),
     };
-    let flag_builder = settings::builder();
+    let mut flag_builder = settings::builder();
+    if enable_simd {
+        flag_builder.enable("enable_simd").unwrap();
+    }
     let isa = isa_builder.finish(settings::Flags::new(flag_builder));
 
     let mut obj = Artifact::new(isa.triple().clone(), String::from(output));
diff --git a/src/wasmtime.rs b/src/wasmtime.rs
index 479efd2915..08b33150b4 100644
--- a/src/wasmtime.rs
+++ b/src/wasmtime.rs
@@ -47,7 +47,7 @@ use std::process::exit;
 use wabt;
 use wasi_common::preopen_dir;
 use wasmtime_environ::cache_conf;
-use wasmtime_jit::{ActionOutcome, Context};
+use wasmtime_jit::{ActionOutcome, Context, Features};
 use wasmtime_wasi::instantiate_wasi;
 use wasmtime_wast::instantiate_spectest;
 
@@ -66,8 +66,8 @@ including calling the start function if one is present. Additional functions
 given with --invoke are then called.
 
 Usage:
-    wasmtime [-ocdg] [--wasi-c] [--preload=<wasm>...] [--env=<env>...] [--dir=<dir>...] [--mapdir=<mapping>...] <file> [<arg>...]
-    wasmtime [-ocdg] [--wasi-c] [--preload=<wasm>...] [--env=<env>...] [--dir=<dir>...] [--mapdir=<mapping>...] --invoke=<fn> <file> [<arg>...]
+    wasmtime [-ocdg] [--enable-simd] [--wasi-c] [--preload=<wasm>...] [--env=<env>...] [--dir=<dir>...] [--mapdir=<mapping>...] <file> [<arg>...]
+    wasmtime [-ocdg] [--enable-simd] [--wasi-c] [--preload=<wasm>...] [--env=<env>...] [--dir=<dir>...] [--mapdir=<mapping>...] --invoke=<fn> <file> [<arg>...]
     wasmtime --help | --version
 
 Options:
@@ -76,6 +76,7 @@ Options:
     -c, --cache         enable caching system
     -g                  generate debug information
     -d, --debug         enable debug output on stderr/stdout
+    --enable-simd       enable proposed SIMD instructions
     --wasi-c            enable the wasi-c implementation of WASI
     --preload=<wasm>    load an additional wasm module before loading the main module
     --env=<env>         pass an environment variable (\"key=value\") to the program
@@ -94,6 +95,7 @@ struct Args {
     flag_cache: bool,
     flag_debug: bool,
     flag_g: bool,
+    flag_enable_simd: bool,
     flag_invoke: Option<String>,
     flag_preload: Vec<String>,
     flag_env: Vec<String>,
@@ -214,19 +216,26 @@ fn main() {
         panic!("host machine is not a supported target");
     });
     let mut flag_builder = settings::builder();
+    let mut features: Features = Default::default();
 
     // Enable verifier passes in debug mode.
     if cfg!(debug_assertions) {
         flag_builder.enable("enable_verifier").unwrap();
     }
 
+    // Enable SIMD if requested
+    if args.flag_enable_simd {
+        flag_builder.enable("enable_simd").unwrap();
+        features.simd = true;
+    }
+
     // Enable optimization if requested.
     if args.flag_optimize {
         flag_builder.set("opt_level", "best").unwrap();
     }
 
     let isa = isa_builder.finish(settings::Flags::new(flag_builder));
-    let mut context = Context::with_isa(isa);
+    let mut context = Context::with_isa(isa).with_features(features);
 
     // Make spectest available by default.
     context.name_instance(
diff --git a/src/wast.rs b/src/wast.rs
index a2af79b87e..49d2ae2b98 100644
--- a/src/wast.rs
+++ b/src/wast.rs
@@ -34,7 +34,7 @@ use serde::Deserialize;
 use std::path::Path;
 use std::process;
 use wasmtime_environ::cache_conf;
-use wasmtime_jit::Compiler;
+use wasmtime_jit::{Compiler, Features};
 use wasmtime_wast::WastContext;
 
 mod utils;
@@ -45,7 +45,7 @@ const USAGE: &str = "
 Wast test runner.
 
 Usage:
-    run_wast [-cdo] <file>...
+    run_wast [-cdo] [--enable-simd] <file>...
     run_wast --help | --version
 
 Options:
@@ -54,6 +54,7 @@ Options:
     -o, --optimize      runs optimization passes on the translated functions
     -c, --cache         enable caching system
     -d, --debug         enable debug output on stderr/stdout
+    --enable-simd       enable proposed SIMD instructions
 ";
 
 #[derive(Deserialize, Debug, Clone)]
@@ -63,6 +64,7 @@ struct Args {
     flag_function: Option<String>,
     flag_optimize: bool,
     flag_cache: bool,
+    flag_enable_simd: bool,
 }
 
 fn main() {
@@ -87,6 +89,7 @@ fn main() {
         panic!("host machine is not a supported target");
     });
     let mut flag_builder = settings::builder();
+    let mut features: Features = Default::default();
 
     // Enable verifier passes in debug mode.
     if cfg!(debug_assertions) {
@@ -98,9 +101,15 @@ fn main() {
         flag_builder.set("opt_level", "best").unwrap();
     }
 
+    // Enable SIMD if requested
+    if args.flag_enable_simd {
+        flag_builder.enable("enable_simd").unwrap();
+        features.simd = true;
+    }
+
     let isa = isa_builder.finish(settings::Flags::new(flag_builder));
     let engine = Compiler::new(isa);
-    let mut wast_context = WastContext::new(Box::new(engine));
+    let mut wast_context = WastContext::new(Box::new(engine)).with_features(features);
 
     wast_context
         .register_spectest()
diff --git a/wasmtime-jit/src/context.rs b/wasmtime-jit/src/context.rs
index 12e710f866..0e2940d678 100644
--- a/wasmtime-jit/src/context.rs
+++ b/wasmtime-jit/src/context.rs
@@ -43,12 +43,43 @@ impl fmt::Display for ContextError {
     }
 }
 
+/// The collection of features configurable during compilation
+#[derive(Clone, Default)]
+pub struct Features {
+    /// marks whether the proposed thread feature is enabled or disabled
+    pub threads: bool,
+    /// marks whether the proposed reference type feature is enabled or disabled
+    pub reference_types: bool,
+    /// marks whether the proposed SIMD feature is enabled or disabled
+    pub simd: bool,
+    /// marks whether the proposed bulk memory feature is enabled or disabled
+    pub bulk_memory: bool,
+    /// marks whether the proposed multi-value feature is enabled or disabled
+    pub multi_value: bool,
+}
+
+impl Into<ValidatingParserConfig> for Features {
+    fn into(self) -> ValidatingParserConfig {
+        ValidatingParserConfig {
+            operator_config: OperatorValidatorConfig {
+                enable_threads: self.threads,
+                enable_reference_types: self.reference_types,
+                enable_bulk_memory: self.bulk_memory,
+                enable_simd: self.simd,
+                enable_multi_value: self.multi_value,
+            },
+            mutable_global_imports: true,
+        }
+    }
+}
+
 /// A convenient context for compiling and executing WebAssembly instances.
 pub struct Context {
     namespace: Namespace,
     compiler: Box<Compiler>,
     global_exports: Rc<RefCell<HashMap<String, Option<wasmtime_runtime::Export>>>>,
     debug_info: bool,
+    features: Features,
 }
 
 impl Context {
@@ -59,6 +90,7 @@ impl Context {
             compiler,
             global_exports: Rc::new(RefCell::new(HashMap::new())),
             debug_info: false,
+            features: Default::default(),
         }
     }
 
@@ -77,21 +109,15 @@ impl Context {
         Self::new(Box::new(Compiler::new(isa)))
     }
 
-    fn validate(&mut self, data: &[u8]) -> Result<(), String> {
-        let config = ValidatingParserConfig {
-            operator_config: OperatorValidatorConfig {
-                enable_threads: false,
-                enable_reference_types: false,
-                enable_bulk_memory: false,
-                enable_simd: false,
-                enable_multi_value: false,
-            },
-            mutable_global_imports: true,
-        };
+    /// Construct a new instance with the given features from the current `Context`
+    pub fn with_features(self, features: Features) -> Self {
+        Self { features, ..self }
+    }
 
+    fn validate(&mut self, data: &[u8]) -> Result<(), String> {
         // TODO: Fix Cranelift to be able to perform validation itself, rather
         // than calling into wasmparser ourselves here.
-        if validate(data, Some(config)) {
+        if validate(data, Some(self.features.clone().into())) {
             Ok(())
         } else {
             // TODO: Work with wasmparser to get better error messages.
diff --git a/wasmtime-jit/src/lib.rs b/wasmtime-jit/src/lib.rs
index 9c878c6b21..3e9dc53b4e 100644
--- a/wasmtime-jit/src/lib.rs
+++ b/wasmtime-jit/src/lib.rs
@@ -51,7 +51,7 @@ mod target_tunables;
 
 pub use crate::action::{ActionError, ActionOutcome, RuntimeValue};
 pub use crate::compiler::Compiler;
-pub use crate::context::{Context, ContextError, UnknownInstance};
+pub use crate::context::{Context, ContextError, Features, UnknownInstance};
 pub use crate::instantiate::{instantiate, CompiledModule, SetupError};
 pub use crate::link::link_module;
 pub use crate::namespace::Namespace;
diff --git a/wasmtime-wast/src/wast.rs b/wasmtime-wast/src/wast.rs
index cf3a10c2eb..2213bdd7ff 100644
--- a/wasmtime-wast/src/wast.rs
+++ b/wasmtime-wast/src/wast.rs
@@ -4,7 +4,7 @@ use std::path::Path;
 use std::{fmt, fs, io, str};
 use wabt::script::{Action, Command, CommandKind, ModuleBinary, ScriptParser, Value};
 use wasmtime_jit::{
-    ActionError, ActionOutcome, Compiler, Context, InstanceHandle, InstantiationError,
+    ActionError, ActionOutcome, Compiler, Context, Features, InstanceHandle, InstantiationError,
     RuntimeValue, UnknownInstance,
 };
 
@@ -85,6 +85,14 @@ impl WastContext {
         }
     }
 
+    /// Construct a new instance with the given features using the current `Context`
+    pub fn with_features(self, features: Features) -> Self {
+        Self {
+            context: self.context.with_features(features),
+            ..self
+        }
+    }
+
     fn get_instance(
         &mut self,
         instance_name: Option<&str>,