diff --git a/src/cmd/tests/aso/meson.build b/src/cmd/tests/aso/meson.build
index f2783a60aec7..d900c5ead1c9 100644
--- a/src/cmd/tests/aso/meson.build
+++ b/src/cmd/tests/aso/meson.build
@@ -11,5 +11,5 @@ foreach file: aso_test_files
                              install: false)
     # TODO: Figure out how to make these tests more efficient so we don't need such an absurdly long
     # timeout in order to keep these tests from timing out on OpenBSD. See issue #483.
-    test('API/' + file, aso_test_target, timeout: 300)
+    test('API/' + file, aso_test_target)
 endforeach
diff --git a/src/cmd/tests/aso/tlock.c b/src/cmd/tests/aso/tlock.c
index bae9f859e1ff..0569bc450a0b 100644
--- a/src/cmd/tests/aso/tlock.c
+++ b/src/cmd/tests/aso/tlock.c
@@ -19,6 +19,8 @@
  ***********************************************************************/
 #include "config_ast.h"  // IWYU pragma: keep
 
+#include <sched.h>
+
 #include "terror.h"
 
 /* Test concurrency locking based on Atomic Scalar Operations
@@ -66,7 +68,7 @@ int lockobj(void *lck, ssize_t size, int locking) {
         return 0;
     }
 
-    for (k = 0;; ++k, usleep(100)) /* locking a slot */
+    for (k = 0;; ++k, sched_yield()) /* locking a slot */
     {
         if (size == sizeof(char))
             aso = asocaschar(lck, 0, Pnum);
@@ -83,7 +85,7 @@ int lockobj(void *lck, ssize_t size, int locking) {
             twarn("Process %3d(pid=%d): locking loop %d blocked by %d", Pnum, Pid[Pnum], k, aso);
     }
 
-    for (k = 0; k < 2; ++k, usleep(100)) /* make sure that lock is good */
+    for (k = 0; k < 2; ++k, sched_yield()) /* make sure that lock is good */
     {
         if (size == sizeof(char))
             lckv = *((char *)lck);
@@ -154,7 +156,7 @@ tmain() {
             continue;
         } else /* child process */
         {
-            for (;; usleep(1000)) /* wait until all are alive */
+            for (;; sched_yield()) /* wait until all are alive */
                 if (*Nproc == N_PROC) break;
             workload(k); /* now start working concurrently */
             texit(0);
diff --git a/src/cmd/tests/cdt/meson.build b/src/cmd/tests/cdt/meson.build
index b6879d81e4db..07d19972fc95 100644
--- a/src/cmd/tests/cdt/meson.build
+++ b/src/cmd/tests/cdt/meson.build
@@ -17,5 +17,5 @@ foreach file: cdt_test_files
                              install: false)
     # TODO: Figure out how to make these tests more efficient so we don't need such an absurdly long
     # timeout in order to keep these tests from timing out on OpenBSD. See issue #483.
-    test('API/' + file, aso_test_target, timeout: 300)
+    test('API/' + file, aso_test_target)
 endforeach
diff --git a/src/cmd/tests/cdt/trehash.c b/src/cmd/tests/cdt/trehash.c
index 35a164ab4028..d09bde98b545 100644
--- a/src/cmd/tests/cdt/trehash.c
+++ b/src/cmd/tests/cdt/trehash.c
@@ -19,9 +19,10 @@
  ***********************************************************************/
 #include "config_ast.h"  // IWYU pragma: keep
 
-#include "dttest.h"
-
 #include <sys/mman.h>
+#include <sched.h>
+
+#include "dttest.h"
 
 /* Test concurrency usage of the method Dtrhset.
 **
@@ -130,7 +131,7 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     /* insert objects in 'p' */
     asoincint(&State->insert);                  /* signaling that we are ready to go */
     while (asogetint(&State->insert) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): insertion passing %d", p, pid, k);
 
@@ -158,12 +159,12 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     tinfo("Process %d(%d): insertion done", p, pid);
     asoincint(&State->idone);            /* signaling that this workload has been inserted */
     while (asogetint(&State->idone) > 0) /* wait until parent signal ok to continue */
-        usleep(100);
+        sched_yield();
 
     /* delete objects in 'p' and also in "foe" of p */
     asoincint(&State->delete);                  /* signaling that we are ready to delete */
     while (asogetint(&State->delete) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): deletion passing %d", p, pid, k);
 
diff --git a/src/cmd/tests/cdt/tsafehash.c b/src/cmd/tests/cdt/tsafehash.c
index e8a2b510d4a2..4c401b587a00 100644
--- a/src/cmd/tests/cdt/tsafehash.c
+++ b/src/cmd/tests/cdt/tsafehash.c
@@ -19,10 +19,11 @@
  ***********************************************************************/
 #include "config_ast.h"  // IWYU pragma: keep
 
-#include "dttest.h"
-
+#include <sched.h>
 #include <sys/mman.h>
 
+#include "dttest.h"
+
 /* Test concurrency usage of the method Dtrhset.
 **
 ** Written by Kiem-Phong Vo
@@ -130,7 +131,7 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     /* insert objects in 'p' */
     asoincint(&State->insert);                  /* signaling that we are ready to go */
     while (asogetint(&State->insert) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): insertion passing %d", p, pid, k);
 
@@ -158,12 +159,12 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     tinfo("Process %d(%d): insertion done", p, pid);
     asoincint(&State->idone);            /* signaling that this workload has been inserted */
     while (asogetint(&State->idone) > 0) /* wait until parent signal ok to continue */
-        usleep(100);
+        sched_yield();
 
     /* delete objects in 'p' and also in "foe" of p */
     asoincint(&State->delete);                  /* signaling that we are ready to delete */
     while (asogetint(&State->delete) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): deletion passing %d", p, pid, k);
 
diff --git a/src/cmd/tests/cdt/tsafetree.c b/src/cmd/tests/cdt/tsafetree.c
index 0d7f0717f3aa..33045565bf22 100644
--- a/src/cmd/tests/cdt/tsafetree.c
+++ b/src/cmd/tests/cdt/tsafetree.c
@@ -19,10 +19,11 @@
  ***********************************************************************/
 #include "config_ast.h"  // IWYU pragma: keep
 
-#include "dttest.h"
-
+#include <sched.h>
 #include <sys/mman.h>
 
+#include "dttest.h"
+
 /* Test concurrency usage of the method Dtrhset.
 **
 ** Written by Kiem-Phong Vo
@@ -131,7 +132,7 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     /* insert objects in 'p' */
     asoincint(&State->insert);                  /* signaling that we are ready to go */
     while (asogetint(&State->insert) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): insertion passing %d", p, pid, k);
 
@@ -159,12 +160,12 @@ static void workload(Dt_t *dt, Proc_t *proc, int p) {
     tinfo("Process %d(%d): insertion done", p, pid);
     asoincint(&State->idone);            /* signaling that this workload has been inserted */
     while (asogetint(&State->idone) > 0) /* wait until parent signal ok to continue */
-        usleep(100);
+        sched_yield();
 
     /* delete objects in 'p' and also in "foe" of p */
     asoincint(&State->delete);                  /* signaling that we are ready to delete */
     while (asogetint(&State->delete) != N_PROC) /* wait until all processes are set */
-        usleep(100);
+        sched_yield();
     for (k = 0; k < proc->objn; ++k) {
         if (k && k % PROGRESS == 0) tinfo("\tProcess %d(%d): deletion passing %d", p, pid, k);