diff --git a/libcxx/test/std/containers/sequences/deque/deque.modifiers/insert_iter_iter.pass.cpp b/libcxx/test/std/containers/sequences/deque/deque.modifiers/insert_iter_iter.pass.cpp
index 946c2cfabf02..4a694e0dd71c 100644
--- a/libcxx/test/std/containers/sequences/deque/deque.modifiers/insert_iter_iter.pass.cpp
+++ b/libcxx/test/std/containers/sequences/deque/deque.modifiers/insert_iter_iter.pass.cpp
@@ -9,6 +9,10 @@
 // REQUIRES: long_tests
 // UNSUPPORTED: GCC-ALWAYS_INLINE-FIXME
 
+// This test chokes on the sanitizers during CI runs. It appears we can address most of this by simply enabling optimizations.
+// ADDITIONAL_COMPILE_FLAGS(msan): -O1
+// ADDITIONAL_COMPILE_FLAGS(tsan): -O1
+
 // <deque>
 
 // template <class InputIterator>
diff --git a/libcxx/test/std/numerics/rand/rand.dist/rand.dist.bern/rand.dist.bern.negbin/eval.pass.cpp b/libcxx/test/std/numerics/rand/rand.dist/rand.dist.bern/rand.dist.bern.negbin/eval.pass.cpp
index d98a73d29666..9ab8b6f42749 100644
--- a/libcxx/test/std/numerics/rand/rand.dist/rand.dist.bern/rand.dist.bern.negbin/eval.pass.cpp
+++ b/libcxx/test/std/numerics/rand/rand.dist/rand.dist.bern/rand.dist.bern.negbin/eval.pass.cpp
@@ -8,6 +8,10 @@
 //
 // REQUIRES: long_tests
 
+// This test is super slow, in particular with msan or tsan. In order to avoid timeouts and to
+// spend less time waiting for this particular test to complete we compile with optimizations.
+// ADDITIONAL_COMPILE_FLAGS: -O1
+
 // <random>
 
 // template<class IntType = int>