diff --git a/crates/wast/src/lib.rs b/crates/wast/src/lib.rs
index c74d1865e1..5d65df137b 100644
--- a/crates/wast/src/lib.rs
+++ b/crates/wast/src/lib.rs
@@ -529,6 +529,8 @@ pub mod kw {
     custom_keyword!(needed);
     custom_keyword!(export_info = "export-info");
     custom_keyword!(import_info = "import-info");
+    custom_keyword!(thread);
+    custom_keyword!(wait);
 }
 
 /// Common annotations used to parse WebAssembly text files.
diff --git a/crates/wast/src/wast.rs b/crates/wast/src/wast.rs
index 1508edb963..1db07e3d14 100644
--- a/crates/wast/src/wast.rs
+++ b/crates/wast/src/wast.rs
@@ -102,6 +102,11 @@ pub enum WastDirective<'a> {
         span: Span,
         exec: WastExecute<'a>,
     },
+    Thread(WastThread<'a>),
+    Wait {
+        span: Span,
+        thread: Id<'a>,
+    },
 }
 
 impl WastDirective<'_> {
@@ -119,8 +124,10 @@ impl WastDirective<'_> {
             | WastDirective::AssertExhaustion { span, .. }
             | WastDirective::AssertUnlinkable { span, .. }
             | WastDirective::AssertInvalid { span, .. }
-            | WastDirective::AssertException { span, .. } => *span,
+            | WastDirective::AssertException { span, .. }
+            | WastDirective::Wait { span, .. } => *span,
             WastDirective::Invoke(i) => i.span,
+            WastDirective::Thread(t) => t.span,
         }
     }
 }
@@ -192,6 +199,14 @@ impl<'a> Parse<'a> for WastDirective<'a> {
                 span,
                 exec: parser.parens(|p| p.parse())?,
             })
+        } else if l.peek::<kw::thread>()? {
+            Ok(WastDirective::Thread(parser.parse()?))
+        } else if l.peek::<kw::wait>()? {
+            let span = parser.parse::<kw::wait>()?.0;
+            Ok(WastDirective::Wait {
+                span,
+                thread: parser.parse()?,
+            })
         } else {
             Err(l.error())
         }
@@ -363,3 +378,49 @@ impl<'a> Parse<'a> for WastRet<'a> {
         }
     }
 }
+
+#[derive(Debug)]
+#[allow(missing_docs)]
+pub struct WastThread<'a> {
+    pub span: Span,
+    pub name: Id<'a>,
+    pub shared_module: Option<Id<'a>>,
+    pub directives: Vec<WastDirective<'a>>,
+}
+
+impl<'a> Parse<'a> for WastThread<'a> {
+    fn parse(parser: Parser<'a>) -> Result<Self> {
+        parser.depth_check()?;
+        let span = parser.parse::<kw::thread>()?.0;
+        let name = parser.parse()?;
+
+        let shared_module = if parser.peek2::<kw::shared>()? {
+            let name = parser.parens(|p| {
+                p.parse::<kw::shared>()?;
+                p.parens(|p| {
+                    p.parse::<kw::module>()?;
+                    p.parse()
+                })
+            })?;
+            Some(name)
+        } else {
+            None
+        };
+        let mut directives = Vec::new();
+        while !parser.is_empty() {
+            directives.push(parser.parens(|p| p.parse())?);
+        }
+        Ok(WastThread {
+            span,
+            name,
+            shared_module,
+            directives,
+        })
+
+        // if parser.peek::<WastRetCore<'_>>()? {
+        //     Ok(WastRet::Core(parser.parse()?))
+        // } else {
+        //     Ok(WastRet::Component(parser.parse()?))
+        // }
+    }
+}
diff --git a/tests/local/upstream-threads/LB.wast b/tests/local/upstream-threads/LB.wast
new file mode 100644
index 0000000000..dc5af8530d
--- /dev/null
+++ b/tests/local/upstream-threads/LB.wast
@@ -0,0 +1,62 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (local i32)
+      (i32.load (i32.const 4))
+      (local.set 0)
+      (i32.store (i32.const 0) (i32.const 1))
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32)
+      (i32.load (i32.const 0))
+      (local.set 0)
+      (i32.store (i32.const 4) (i32.const 1))
+
+      ;; store results for checking
+      (i32.store (i32.const 32) (local.get 0))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 0 || L_0 = 1) && (L_1 = 0 || L_1 = 1)
+
+    (i32.or (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.or (i32.eq (local.get 1) (i32.const 1)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.and)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/LB_atomic.wast b/tests/local/upstream-threads/LB_atomic.wast
new file mode 100644
index 0000000000..79642713a4
--- /dev/null
+++ b/tests/local/upstream-threads/LB_atomic.wast
@@ -0,0 +1,64 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (local i32)
+      (i32.atomic.load (i32.const 4))
+      (local.set 0)
+      (i32.atomic.store (i32.const 0) (i32.const 1))
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32)
+      (i32.atomic.load (i32.const 0))
+      (local.set 0)
+      (i32.atomic.store (i32.const 4) (i32.const 1))
+
+      ;; store results for checking
+      (i32.store (i32.const 32) (local.get 0))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 0 && L_1 = 0) || (L_0 = 0 && L_1 = 1) || (L_0 = 1 && L_1 = 0)
+
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 0)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 1)))
+    (i32.and (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 1) (i32.const 0)))
+    (i32.or)
+    (i32.or)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/MP.wast b/tests/local/upstream-threads/MP.wast
new file mode 100644
index 0000000000..e14508596f
--- /dev/null
+++ b/tests/local/upstream-threads/MP.wast
@@ -0,0 +1,59 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (i32.store (i32.const 0) (i32.const 42))
+      (i32.store (i32.const 4) (i32.const 1))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32 i32)
+      (i32.load (i32.const 4))
+      (local.set 0)
+      (i32.load (i32.const 0))
+      (local.set 1)
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+      (i32.store (i32.const 32) (local.get 1))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 0 || L_0 = 1) && (L_1 = 0 || L_1 = 42)
+
+    (i32.or (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.or (i32.eq (local.get 1) (i32.const 42)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.and)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/MP_atomic.wast b/tests/local/upstream-threads/MP_atomic.wast
new file mode 100644
index 0000000000..2001634a22
--- /dev/null
+++ b/tests/local/upstream-threads/MP_atomic.wast
@@ -0,0 +1,61 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (i32.atomic.store (i32.const 0) (i32.const 42))
+      (i32.atomic.store (i32.const 4) (i32.const 1))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32 i32)
+      (i32.atomic.load (i32.const 4))
+      (local.set 0)
+      (i32.atomic.load (i32.const 0))
+      (local.set 1)
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+      (i32.store (i32.const 32) (local.get 1))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 1 && L_1 = 42) || (L_0 = 0 && L_1 = 0) || (L_0 = 0 && L_1 = 42)
+
+    (i32.and (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 1) (i32.const 42)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 0)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 42)))
+    (i32.or)
+    (i32.or)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/MP_wait.wast b/tests/local/upstream-threads/MP_wait.wast
new file mode 100644
index 0000000000..2001634a22
--- /dev/null
+++ b/tests/local/upstream-threads/MP_wait.wast
@@ -0,0 +1,61 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (i32.atomic.store (i32.const 0) (i32.const 42))
+      (i32.atomic.store (i32.const 4) (i32.const 1))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32 i32)
+      (i32.atomic.load (i32.const 4))
+      (local.set 0)
+      (i32.atomic.load (i32.const 0))
+      (local.set 1)
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+      (i32.store (i32.const 32) (local.get 1))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 1 && L_1 = 42) || (L_0 = 0 && L_1 = 0) || (L_0 = 0 && L_1 = 42)
+
+    (i32.and (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 1) (i32.const 42)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 0)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 42)))
+    (i32.or)
+    (i32.or)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/SB.wast b/tests/local/upstream-threads/SB.wast
new file mode 100644
index 0000000000..65fe7853d8
--- /dev/null
+++ b/tests/local/upstream-threads/SB.wast
@@ -0,0 +1,62 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (local i32)
+      (i32.store (i32.const 0) (i32.const 1))
+      (i32.load (i32.const 4))
+      (local.set 0)
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32)
+      (i32.store (i32.const 4) (i32.const 1))
+      (i32.load (i32.const 0))
+      (local.set 0)
+
+      ;; store results for checking
+      (i32.store (i32.const 32) (local.get 0))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 0 || L_0 = 1) && (L_1 = 0 || L_1 = 1)
+
+    (i32.or (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.or (i32.eq (local.get 1) (i32.const 1)) (i32.eq (local.get 0) (i32.const 0)))
+    (i32.and)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/SB_atomic.wast b/tests/local/upstream-threads/SB_atomic.wast
new file mode 100644
index 0000000000..3bd8c8a6db
--- /dev/null
+++ b/tests/local/upstream-threads/SB_atomic.wast
@@ -0,0 +1,64 @@
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run")
+      (local i32)
+      (i32.atomic.store (i32.const 0) (i32.const 1))
+      (i32.atomic.load (i32.const 4))
+      (local.set 0)
+
+      ;; store results for checking
+      (i32.store (i32.const 24) (local.get 0))
+    )
+  )
+  (invoke "run")
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "run")
+      (local i32)
+      (i32.atomic.store (i32.const 4) (i32.const 1))
+      (i32.atomic.load (i32.const 0))
+      (local.set 0)
+
+      ;; store results for checking
+      (i32.store (i32.const 32) (local.get 0))
+    )
+  )
+
+  (invoke "run")
+)
+
+(wait $T1)
+(wait $T2)
+
+(module $Check
+  (memory (import "mem" "shared") 1 1 shared)
+
+  (func (export "check") (result i32)
+    (local i32 i32)
+    (i32.load (i32.const 24))
+    (local.set 0)
+    (i32.load (i32.const 32))
+    (local.set 1)
+
+    ;; allowed results: (L_0 = 1 && L_1 = 1) || (L_0 = 0 && L_1 = 1) || (L_0 = 1 && L_1 = 0)
+
+    (i32.and (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 1) (i32.const 1)))
+    (i32.and (i32.eq (local.get 0) (i32.const 0)) (i32.eq (local.get 1) (i32.const 1)))
+    (i32.and (i32.eq (local.get 0) (i32.const 1)) (i32.eq (local.get 1) (i32.const 0)))
+    (i32.or)
+    (i32.or)
+    (return)
+  )
+)
+
+(assert_return (invoke $Check "check") (i32.const 1))
diff --git a/tests/local/upstream-threads/wait_notify.wast b/tests/local/upstream-threads/wait_notify.wast
new file mode 100644
index 0000000000..270509a92d
--- /dev/null
+++ b/tests/local/upstream-threads/wait_notify.wast
@@ -0,0 +1,41 @@
+;; test that looping notify eventually unblocks a parallel waiting thread
+(module $Mem
+  (memory (export "shared") 1 1 shared)
+)
+
+(thread $T1 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 10 shared)
+    (func (export "run") (result i32)
+      (memory.atomic.wait32 (i32.const 0) (i32.const 0) (i64.const -1))
+    )
+  )
+  ;; test that this thread eventually gets unblocked
+  (assert_return (invoke "run") (i32.const 0))
+)
+
+(thread $T2 (shared (module $Mem))
+  (register "mem" $Mem)
+  (module
+    (memory (import "mem" "shared") 1 1 shared)
+    (func (export "notify-0") (result i32)
+      (memory.atomic.notify (i32.const 0) (i32.const 0))
+    )
+    (func (export "notify-1-while")
+      (loop
+        (i32.const 1)
+        (memory.atomic.notify (i32.const 0) (i32.const 1))
+        (i32.ne)
+        (br_if 0)
+      )
+    )
+  )
+  ;; notifying with a count of 0 will not unblock
+  (assert_return (invoke "notify-0") (i32.const 0))
+  ;; loop until something is notified
+  (assert_return (invoke "notify-1-while"))
+)
+
+(wait $T1)
+(wait $T2)
diff --git a/tests/roundtrip.rs b/tests/roundtrip.rs
index 2262b3b221..d42f956ab3 100644
--- a/tests/roundtrip.rs
+++ b/tests/roundtrip.rs
@@ -417,6 +417,12 @@ impl TestState {
                 }
             }
 
+            WastDirective::Thread(thread) => {
+                for (i, directive) in thread.directives.into_iter().enumerate() {
+                    self.test_wast_directive(test, directive, idx * 1000 + i)?;
+                }
+            }
+
             // This test suite doesn't actually execute any wasm code, so ignore
             // all of these assertions.
             WastDirective::Register { .. }
@@ -425,7 +431,8 @@ impl TestState {
             | WastDirective::AssertReturn { .. }
             | WastDirective::AssertExhaustion { .. }
             | WastDirective::AssertUnlinkable { .. }
-            | WastDirective::AssertException { .. } => {}
+            | WastDirective::AssertException { .. }
+            | WastDirective::Wait { .. } => {}
         }
         Ok(())
     }
diff --git a/tests/snapshots/local/upstream-threads/LB.wast/0.print b/tests/snapshots/local/upstream-threads/LB.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB.wast/1001.print b/tests/snapshots/local/upstream-threads/LB.wast/1001.print
new file mode 100644
index 0000000000..ec4622d267
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB.wast/1001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 4
+    i32.load
+    local.set 0
+    i32.const 0
+    i32.const 1
+    i32.store
+    i32.const 24
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB.wast/2001.print b/tests/snapshots/local/upstream-threads/LB.wast/2001.print
new file mode 100644
index 0000000000..4d46596968
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB.wast/2001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 0
+    i32.load
+    local.set 0
+    i32.const 4
+    i32.const 1
+    i32.store
+    i32.const 32
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB.wast/5.print b/tests/snapshots/local/upstream-threads/LB.wast/5.print
new file mode 100644
index 0000000000..c5a71158bd
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB.wast/5.print
@@ -0,0 +1,30 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    local.get 1
+    i32.const 1
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    i32.and
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB_atomic.wast/0.print b/tests/snapshots/local/upstream-threads/LB_atomic.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB_atomic.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB_atomic.wast/1001.print b/tests/snapshots/local/upstream-threads/LB_atomic.wast/1001.print
new file mode 100644
index 0000000000..970c0227f9
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB_atomic.wast/1001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 4
+    i32.atomic.load
+    local.set 0
+    i32.const 0
+    i32.const 1
+    i32.atomic.store
+    i32.const 24
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB_atomic.wast/2001.print b/tests/snapshots/local/upstream-threads/LB_atomic.wast/2001.print
new file mode 100644
index 0000000000..30a2619d1b
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB_atomic.wast/2001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 0
+    i32.atomic.load
+    local.set 0
+    i32.const 4
+    i32.const 1
+    i32.atomic.store
+    i32.const 32
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/LB_atomic.wast/5.print b/tests/snapshots/local/upstream-threads/LB_atomic.wast/5.print
new file mode 100644
index 0000000000..e883dc159e
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/LB_atomic.wast/5.print
@@ -0,0 +1,38 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 0
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 1
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 1
+    i32.const 0
+    i32.eq
+    i32.and
+    i32.or
+    i32.or
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP.wast/0.print b/tests/snapshots/local/upstream-threads/MP.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP.wast/1001.print b/tests/snapshots/local/upstream-threads/MP.wast/1001.print
new file mode 100644
index 0000000000..b2aa175be7
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP.wast/1001.print
@@ -0,0 +1,13 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    i32.const 0
+    i32.const 42
+    i32.store
+    i32.const 4
+    i32.const 1
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP.wast/2001.print b/tests/snapshots/local/upstream-threads/MP.wast/2001.print
new file mode 100644
index 0000000000..48117d8458
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP.wast/2001.print
@@ -0,0 +1,20 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32 i32)
+    i32.const 4
+    i32.load
+    local.set 0
+    i32.const 0
+    i32.load
+    local.set 1
+    i32.const 24
+    local.get 0
+    i32.store
+    i32.const 32
+    local.get 1
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP.wast/5.print b/tests/snapshots/local/upstream-threads/MP.wast/5.print
new file mode 100644
index 0000000000..f7f4a0a7e3
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP.wast/5.print
@@ -0,0 +1,30 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    local.get 1
+    i32.const 42
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    i32.and
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_atomic.wast/0.print b/tests/snapshots/local/upstream-threads/MP_atomic.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_atomic.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_atomic.wast/1001.print b/tests/snapshots/local/upstream-threads/MP_atomic.wast/1001.print
new file mode 100644
index 0000000000..1daa6c6003
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_atomic.wast/1001.print
@@ -0,0 +1,13 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    i32.const 0
+    i32.const 42
+    i32.atomic.store
+    i32.const 4
+    i32.const 1
+    i32.atomic.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_atomic.wast/2001.print b/tests/snapshots/local/upstream-threads/MP_atomic.wast/2001.print
new file mode 100644
index 0000000000..746ccf24a9
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_atomic.wast/2001.print
@@ -0,0 +1,20 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32 i32)
+    i32.const 4
+    i32.atomic.load
+    local.set 0
+    i32.const 0
+    i32.atomic.load
+    local.set 1
+    i32.const 24
+    local.get 0
+    i32.store
+    i32.const 32
+    local.get 1
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_atomic.wast/5.print b/tests/snapshots/local/upstream-threads/MP_atomic.wast/5.print
new file mode 100644
index 0000000000..ef8b3cd066
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_atomic.wast/5.print
@@ -0,0 +1,38 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 1
+    i32.const 42
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 0
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 42
+    i32.eq
+    i32.and
+    i32.or
+    i32.or
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_wait.wast/0.print b/tests/snapshots/local/upstream-threads/MP_wait.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_wait.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_wait.wast/1001.print b/tests/snapshots/local/upstream-threads/MP_wait.wast/1001.print
new file mode 100644
index 0000000000..1daa6c6003
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_wait.wast/1001.print
@@ -0,0 +1,13 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    i32.const 0
+    i32.const 42
+    i32.atomic.store
+    i32.const 4
+    i32.const 1
+    i32.atomic.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_wait.wast/2001.print b/tests/snapshots/local/upstream-threads/MP_wait.wast/2001.print
new file mode 100644
index 0000000000..746ccf24a9
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_wait.wast/2001.print
@@ -0,0 +1,20 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32 i32)
+    i32.const 4
+    i32.atomic.load
+    local.set 0
+    i32.const 0
+    i32.atomic.load
+    local.set 1
+    i32.const 24
+    local.get 0
+    i32.store
+    i32.const 32
+    local.get 1
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/MP_wait.wast/5.print b/tests/snapshots/local/upstream-threads/MP_wait.wast/5.print
new file mode 100644
index 0000000000..ef8b3cd066
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/MP_wait.wast/5.print
@@ -0,0 +1,38 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 1
+    i32.const 42
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 0
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 42
+    i32.eq
+    i32.and
+    i32.or
+    i32.or
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB.wast/0.print b/tests/snapshots/local/upstream-threads/SB.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB.wast/1001.print b/tests/snapshots/local/upstream-threads/SB.wast/1001.print
new file mode 100644
index 0000000000..07591f2cd3
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB.wast/1001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 0
+    i32.const 1
+    i32.store
+    i32.const 4
+    i32.load
+    local.set 0
+    i32.const 24
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB.wast/2001.print b/tests/snapshots/local/upstream-threads/SB.wast/2001.print
new file mode 100644
index 0000000000..c39039b89b
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB.wast/2001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 4
+    i32.const 1
+    i32.store
+    i32.const 0
+    i32.load
+    local.set 0
+    i32.const 32
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB.wast/5.print b/tests/snapshots/local/upstream-threads/SB.wast/5.print
new file mode 100644
index 0000000000..c5a71158bd
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB.wast/5.print
@@ -0,0 +1,30 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    local.get 1
+    i32.const 1
+    i32.eq
+    local.get 0
+    i32.const 0
+    i32.eq
+    i32.or
+    i32.and
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB_atomic.wast/0.print b/tests/snapshots/local/upstream-threads/SB_atomic.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB_atomic.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB_atomic.wast/1001.print b/tests/snapshots/local/upstream-threads/SB_atomic.wast/1001.print
new file mode 100644
index 0000000000..ee37e48867
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB_atomic.wast/1001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 0
+    i32.const 1
+    i32.atomic.store
+    i32.const 4
+    i32.atomic.load
+    local.set 0
+    i32.const 24
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB_atomic.wast/2001.print b/tests/snapshots/local/upstream-threads/SB_atomic.wast/2001.print
new file mode 100644
index 0000000000..4d51cd1684
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB_atomic.wast/2001.print
@@ -0,0 +1,17 @@
+(module
+  (type (;0;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0)
+    (local i32)
+    i32.const 4
+    i32.const 1
+    i32.atomic.store
+    i32.const 0
+    i32.atomic.load
+    local.set 0
+    i32.const 32
+    local.get 0
+    i32.store
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/SB_atomic.wast/5.print b/tests/snapshots/local/upstream-threads/SB_atomic.wast/5.print
new file mode 100644
index 0000000000..12c951ddb9
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/SB_atomic.wast/5.print
@@ -0,0 +1,38 @@
+(module $Check
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    (local i32 i32)
+    i32.const 24
+    i32.load
+    local.set 0
+    i32.const 32
+    i32.load
+    local.set 1
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 1
+    i32.const 1
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 0
+    i32.eq
+    local.get 1
+    i32.const 1
+    i32.eq
+    i32.and
+    local.get 0
+    i32.const 1
+    i32.eq
+    local.get 1
+    i32.const 0
+    i32.eq
+    i32.and
+    i32.or
+    i32.or
+    return
+  )
+  (export "check" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/wait_notify.wast/0.print b/tests/snapshots/local/upstream-threads/wait_notify.wast/0.print
new file mode 100644
index 0000000000..0c5fc57030
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/wait_notify.wast/0.print
@@ -0,0 +1,4 @@
+(module $Mem
+  (memory (;0;) 1 1 shared)
+  (export "shared" (memory 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/wait_notify.wast/1001.print b/tests/snapshots/local/upstream-threads/wait_notify.wast/1001.print
new file mode 100644
index 0000000000..36210b6062
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/wait_notify.wast/1001.print
@@ -0,0 +1,11 @@
+(module
+  (type (;0;) (func (result i32)))
+  (import "mem" "shared" (memory (;0;) 1 10 shared))
+  (func (;0;) (type 0) (result i32)
+    i32.const 0
+    i32.const 0
+    i64.const -1
+    memory.atomic.wait32
+  )
+  (export "run" (func 0))
+)
\ No newline at end of file
diff --git a/tests/snapshots/local/upstream-threads/wait_notify.wast/2001.print b/tests/snapshots/local/upstream-threads/wait_notify.wast/2001.print
new file mode 100644
index 0000000000..4c749f4783
--- /dev/null
+++ b/tests/snapshots/local/upstream-threads/wait_notify.wast/2001.print
@@ -0,0 +1,22 @@
+(module
+  (type (;0;) (func (result i32)))
+  (type (;1;) (func))
+  (import "mem" "shared" (memory (;0;) 1 1 shared))
+  (func (;0;) (type 0) (result i32)
+    i32.const 0
+    i32.const 0
+    memory.atomic.notify
+  )
+  (func (;1;) (type 1)
+    loop ;; label = @1
+      i32.const 1
+      i32.const 0
+      i32.const 1
+      memory.atomic.notify
+      i32.ne
+      br_if 0 (;@1;)
+    end
+  )
+  (export "notify-0" (func 0))
+  (export "notify-1-while" (func 1))
+)
\ No newline at end of file