diff --git a/src/libcore/tests/num/dec2flt/mod.rs b/src/libcore/tests/num/dec2flt/mod.rs
index 5d546c643e7..9934e1dab96 100644
--- a/src/libcore/tests/num/dec2flt/mod.rs
+++ b/src/libcore/tests/num/dec2flt/mod.rs
@@ -33,6 +33,7 @@ macro_rules! test_literal {
     })
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn ordinary() {
     test_literal!(1.0);
@@ -43,6 +44,7 @@ fn ordinary() {
     test_literal!(2.2250738585072014e-308);
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn special_code_paths() {
     test_literal!(36893488147419103229.0); // 2^65 - 3, triggers half-to-even with even significand
diff --git a/src/libcore/tests/num/dec2flt/rawfp.rs b/src/libcore/tests/num/dec2flt/rawfp.rs
index 2b0afc40202..c9cd2bf5a9a 100644
--- a/src/libcore/tests/num/dec2flt/rawfp.rs
+++ b/src/libcore/tests/num/dec2flt/rawfp.rs
@@ -86,6 +86,7 @@ fn rounding_overflow() {
     assert_eq!(rounded.k, adjusted_k + 1);
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn prev_float_monotonic() {
     let mut x = 1.0;
@@ -121,6 +122,7 @@ fn next_float_inf() {
     assert_eq!(next_float(f64::INFINITY), f64::INFINITY);
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn next_prev_identity() {
     for &x in &SOME_FLOATS {
@@ -131,6 +133,7 @@ fn next_prev_identity() {
     }
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn next_float_monotonic() {
     let mut x = 0.49999999999999;
diff --git a/src/libcore/tests/num/flt2dec/strategy/dragon.rs b/src/libcore/tests/num/flt2dec/strategy/dragon.rs
index 4edb0f3df60..03772a765cc 100644
--- a/src/libcore/tests/num/flt2dec/strategy/dragon.rs
+++ b/src/libcore/tests/num/flt2dec/strategy/dragon.rs
@@ -24,6 +24,7 @@ fn test_mul_pow10() {
     }
 }
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn shortest_sanity_test() {
     f64_shortest_sanity_test(format_shortest);
diff --git a/src/libcore/tests/num/flt2dec/strategy/grisu.rs b/src/libcore/tests/num/flt2dec/strategy/grisu.rs
index 79e66ee669e..17fb99bcc92 100644
--- a/src/libcore/tests/num/flt2dec/strategy/grisu.rs
+++ b/src/libcore/tests/num/flt2dec/strategy/grisu.rs
@@ -38,6 +38,7 @@ fn test_max_pow10_no_more_than() {
 }
 
 
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn shortest_sanity_test() {
     f64_shortest_sanity_test(format_shortest);
diff --git a/src/libcore/tests/num/mod.rs b/src/libcore/tests/num/mod.rs
index 51737c9c3b4..8fdcc36a268 100644
--- a/src/libcore/tests/num/mod.rs
+++ b/src/libcore/tests/num/mod.rs
@@ -169,6 +169,7 @@ test_impl_from! { test_u16f64, u16, f64 }
 test_impl_from! { test_u32f64, u32, f64 }
 
 // Float -> Float
+#[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
 #[test]
 fn test_f32f64() {
     use core::f32;
diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs
index 82e3903eec7..813998b7502 100644
--- a/src/libstd/f64.rs
+++ b/src/libstd/f64.rs
@@ -1158,6 +1158,7 @@ mod tests {
         assert_eq!(Fp::Zero, neg_zero.classify());
     }
 
+    #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
     #[test]
     fn test_one() {
         let one: f64 = 1.0f64;
@@ -1210,6 +1211,7 @@ mod tests {
         assert!((-109.2f64).is_finite());
     }
 
+    #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
     #[test]
     fn test_is_normal() {
         let nan: f64 = NAN;
@@ -1227,6 +1229,7 @@ mod tests {
         assert!(!1e-308f64.is_normal());
     }
 
+    #[cfg_attr(all(target_arch = "wasm32", target_os = "emscripten"), ignore)] // issue 42630
     #[test]
     fn test_classify() {
         let nan: f64 = NAN;
diff --git a/src/test/run-pass/asm-concat-src.rs b/src/test/run-pass/asm-concat-src.rs
index ea3d0c3aa0e..fb257bf7b50 100644
--- a/src/test/run-pass/asm-concat-src.rs
+++ b/src/test/run-pass/asm-concat-src.rs
@@ -9,7 +9,7 @@
 // except according to those terms.
 
 // pretty-expanded FIXME #23616
-// ignore-asmjs
+// ignore-emscripten
 
 #![feature(asm)]
 
diff --git a/src/test/run-pass/conditional-compile-arch.rs b/src/test/run-pass/conditional-compile-arch.rs
index 24c461d5f51..6e3e4be0d8e 100644
--- a/src/test/run-pass/conditional-compile-arch.rs
+++ b/src/test/run-pass/conditional-compile-arch.rs
@@ -36,3 +36,6 @@ pub fn main() { }
 
 #[cfg(target_arch = "asmjs")]
 pub fn main() { }
+
+#[cfg(target_arch = "wasm32")]
+pub fn main() { }
diff --git a/src/test/run-pass/issue-27859.rs b/src/test/run-pass/issue-27859.rs
index 900614be612..56036caca15 100644
--- a/src/test/run-pass/issue-27859.rs
+++ b/src/test/run-pass/issue-27859.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// ignore-wasm32 issue 42629
+
 #[inline(never)]
 fn foo(a: f32, b: f32) -> f32 {
     a % b
diff --git a/src/test/run-pass/out-of-stack.rs b/src/test/run-pass/out-of-stack.rs
index a7748b6d6a2..7e70c4a7ab3 100644
--- a/src/test/run-pass/out-of-stack.rs
+++ b/src/test/run-pass/out-of-stack.rs
@@ -10,7 +10,7 @@
 
 // ignore-android: FIXME (#20004)
 // ignore-musl
-// ignore-asmjs
+// ignore-emscripten
 
 #![feature(asm)]
 #![feature(libc)]