diff --git a/library/alloc/benches/btree/map.rs b/library/alloc/benches/btree/map.rs
index b8119c9f0eb..5b15aaeddbc 100644
--- a/library/alloc/benches/btree/map.rs
+++ b/library/alloc/benches/btree/map.rs
@@ -353,6 +353,7 @@ pub fn iter_10k(b: &mut Bencher) {
 }
 
 #[bench]
+#[cfg_attr(target_os = "emscripten", ignore)] // hits an OOM
 pub fn iter_1m(b: &mut Bencher) {
     bench_iter(b, 1_000, 1_000_000);
 }
diff --git a/library/alloc/benches/slice.rs b/library/alloc/benches/slice.rs
index 48c74c4491d..c45c3722712 100644
--- a/library/alloc/benches/slice.rs
+++ b/library/alloc/benches/slice.rs
@@ -366,14 +366,25 @@ rotate!(rotate_medium_half, gen_random, 9158, 9158 / 2);
 rotate!(rotate_medium_half_plus_one, gen_random, 9158, 9158 / 2 + 1);
 
 // Intended to use more RAM than the machine has cache
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by1, gen_random, 5 * 1024 * 1024, 1);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by9199_u64, gen_random, 5 * 1024 * 1024, 9199);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by9199_bytes, gen_random_bytes, 5 * 1024 * 1024, 9199);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by9199_strings, gen_strings, 5 * 1024 * 1024, 9199);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by9199_big, gen_big_random, 5 * 1024 * 1024, 9199);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by1234577_u64, gen_random, 5 * 1024 * 1024, 1234577);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by1234577_bytes, gen_random_bytes, 5 * 1024 * 1024, 1234577);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by1234577_strings, gen_strings, 5 * 1024 * 1024, 1234577);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_by1234577_big, gen_big_random, 5 * 1024 * 1024, 1234577);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_half, gen_random, 5 * 1024 * 1024, 5 * 1024 * 1024 / 2);
+#[cfg(not(target_os = "emscripten"))] // hits an OOM
 rotate!(rotate_huge_half_plus_one, gen_random, 5 * 1024 * 1024, 5 * 1024 * 1024 / 2 + 1);
diff --git a/library/alloc/benches/vec.rs b/library/alloc/benches/vec.rs
index d29ffae9d70..a725ad6894b 100644
--- a/library/alloc/benches/vec.rs
+++ b/library/alloc/benches/vec.rs
@@ -547,6 +547,11 @@ fn bench_in_place_collect_droppable(b: &mut Bencher) {
     })
 }
 
+// node.js gives out of memory error to use with length 1_100_000
+#[cfg(target_os = "emscripten")]
+const LEN: usize = 4096;
+
+#[cfg(not(target_os = "emscripten"))]
 const LEN: usize = 16384;
 
 #[bench]
diff --git a/library/alloc/tests/sort/tests.rs b/library/alloc/tests/sort/tests.rs
index 4cc79010e8f..d321f8df518 100644
--- a/library/alloc/tests/sort/tests.rs
+++ b/library/alloc/tests/sort/tests.rs
@@ -11,7 +11,14 @@ use crate::sort::{Sort, known_good_stable_sort, patterns};
 #[cfg(miri)]
 const TEST_LENGTHS: &[usize] = &[2, 3, 4, 7, 10, 15, 20, 24, 33, 50, 100, 171, 300];
 
-#[cfg(not(miri))]
+// node.js gives out of memory error to use with length 1_100_000
+#[cfg(all(not(miri), target_os = "emscripten"))]
+const TEST_LENGTHS: &[usize] = &[
+    2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 20, 24, 30, 32, 33, 35, 50, 100, 200, 500, 1_000,
+    2_048, 5_000, 10_000, 100_000,
+];
+
+#[cfg(all(not(miri), not(target_os = "emscripten")))]
 const TEST_LENGTHS: &[usize] = &[
     2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 16, 17, 20, 24, 30, 32, 33, 35, 50, 100, 200, 500, 1_000,
     2_048, 5_000, 10_000, 100_000, 1_100_000,
diff --git a/library/alloc/tests/sync.rs b/library/alloc/tests/sync.rs
index 7a9a4abfdc6..6d3ab1b1d11 100644
--- a/library/alloc/tests/sync.rs
+++ b/library/alloc/tests/sync.rs
@@ -128,6 +128,7 @@ fn try_unwrap() {
 }
 
 #[test]
+#[cfg_attr(any(target_os = "emscripten", target_os = "wasi"), ignore)] // no threads
 fn into_inner() {
     for _ in 0..100
     // ^ Increase chances of hitting potential race conditions
diff --git a/library/std/src/io/copy/tests.rs b/library/std/src/io/copy/tests.rs
index 2e0eb6cdce6..25b1ece2745 100644
--- a/library/std/src/io/copy/tests.rs
+++ b/library/std/src/io/copy/tests.rs
@@ -126,6 +126,7 @@ mod io_benches {
     use crate::io::prelude::*;
 
     #[bench]
+    #[cfg_attr(target_os = "emscripten", ignore)] // no /dev
     fn bench_copy_buf_reader(b: &mut Bencher) {
         let mut file_in = File::open("/dev/zero").expect("opening /dev/zero failed");
         // use dyn to avoid specializations unrelated to readbuf
diff --git a/library/std/tests/pipe_subprocess.rs b/library/std/tests/pipe_subprocess.rs
index df946cdcf2b..00d99a578d5 100644
--- a/library/std/tests/pipe_subprocess.rs
+++ b/library/std/tests/pipe_subprocess.rs
@@ -1,7 +1,7 @@
 #![feature(anonymous_pipe)]
 
 fn main() {
-    #[cfg(all(not(miri), any(unix, windows)))]
+    #[cfg(all(not(miri), any(unix, windows), not(target_os = "emscripten")))]
     {
         use std::io::{Read, pipe};
         use std::{env, process};
diff --git a/library/std/tests/process_spawning.rs b/library/std/tests/process_spawning.rs
index 3e72e371ade..43b45cb2d2b 100644
--- a/library/std/tests/process_spawning.rs
+++ b/library/std/tests/process_spawning.rs
@@ -5,7 +5,8 @@ use std::{env, fs, process, str};
 mod common;
 
 #[test]
-#[cfg_attr(any(miri, target_os = "wasi"), ignore)] // Process spawning not supported by Miri and wasi
+// Process spawning not supported by Miri, Emscripten and wasi
+#[cfg_attr(any(miri, target_os = "emscripten", target_os = "wasi"), ignore)]
 fn issue_15149() {
     // If we're the parent, copy our own binary to a new directory.
     let my_path = env::current_exe().unwrap();