diff --git a/renderdoc/os/os_specific.h b/renderdoc/os/os_specific.h
index 88100ca17..471223cbf 100644
--- a/renderdoc/os/os_specific.h
+++ b/renderdoc/os/os_specific.h
@@ -146,6 +146,17 @@ uint64_t AllocateTLSSlot();
 void *GetTLSValue(uint64_t slot);
 void SetTLSValue(uint64_t slot, void *value);
 
+struct Semaphore
+{
+  static Semaphore *Create();
+  void Destroy();
+  void Wake(uint32_t numToWake);
+  void WaitForWake();
+protected:
+  Semaphore();
+  ~Semaphore();
+};
+
 // must typedef CriticalSectionTemplate<X> CriticalSection
 
 void SetCurrentThreadName(const rdcstr &name);
diff --git a/renderdoc/os/posix/android/android_threading.cpp b/renderdoc/os/posix/android/android_threading.cpp
index 58474fcbd..73700aa0b 100644
--- a/renderdoc/os/posix/android/android_threading.cpp
+++ b/renderdoc/os/posix/android/android_threading.cpp
@@ -24,6 +24,10 @@
 
 #include "os/os_specific.h"
 
+#include "common/common.h"
+
+#include <errno.h>
+#include <semaphore.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -42,3 +46,67 @@ uint64_t Timing::GetTick()
 void Threading::SetCurrentThreadName(const rdcstr &name)
 {
 }
+
+namespace Threading
+{
+
+// works for all posix except apple, hence being here
+struct PosixSemaphore : public Semaphore
+{
+  ~PosixSemaphore() {}
+
+  sem_t h;
+};
+
+Semaphore *Semaphore::Create()
+{
+  PosixSemaphore *sem = new PosixSemaphore();
+  int err = sem_init(&sem->h, 0, 0);
+  // only documented errors are too large initial value (impossible for 0) or for shared semaphores
+  // going wrong (we're not shared)
+  RDCASSERT(err == 0, errno);
+  return sem;
+}
+
+void Semaphore::Destroy()
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+  sem_destroy(&sem->h);
+  delete sem;
+}
+
+void Semaphore::Wake(uint32_t numToWake)
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+  for(uint32_t i = 0; i < numToWake; i++)
+    sem_post(&sem->h);
+}
+
+void Semaphore::WaitForWake()
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+
+  // handle extremely moronic stupid signal interruptions
+  do
+  {
+    int ret = sem_wait(&sem->h);
+
+    if(ret == -1)
+    {
+      if(errno == EINTR)
+        continue;
+
+      RDCWARN("Semaphore wait failed: %d", errno);
+    }
+  } while(false);
+}
+
+Semaphore::Semaphore()
+{
+}
+
+Semaphore::~Semaphore()
+{
+}
+
+};
diff --git a/renderdoc/os/posix/apple/apple_threading.cpp b/renderdoc/os/posix/apple/apple_threading.cpp
index 3c88b26c5..068a31232 100644
--- a/renderdoc/os/posix/apple/apple_threading.cpp
+++ b/renderdoc/os/posix/apple/apple_threading.cpp
@@ -24,6 +24,7 @@
 
 #include "os/os_specific.h"
 
+#include <dispatch/dispatch.h>
 #include <mach/mach_time.h>
 
 double Timing::GetTickFrequency()
@@ -44,3 +45,51 @@ uint64_t Timing::GetTick()
 void Threading::SetCurrentThreadName(const rdcstr &name)
 {
 }
+
+namespace Threading
+{
+
+struct AppleSemaphore : public Semaphore
+{
+  ~AppleSemaphore() {}
+
+  dispatch_semaphore_t h;
+};
+
+Semaphore *Semaphore::Create()
+{
+  AppleSemaphore *sem = new AppleSemaphore();
+  sem->h = dispatch_semaphore_create(0);
+  return sem;
+}
+
+void Semaphore::Destroy()
+{
+  AppleSemaphore *sem = (AppleSemaphore *)this;
+  dispatch_release(sem->h);
+  delete sem;
+}
+
+void Semaphore::Wake(uint32_t numToWake)
+{
+  AppleSemaphore *sem = (AppleSemaphore *)this;
+  for(uint32_t i = 0; i < numToWake; i++)
+    dispatch_semaphore_signal(sem->h);
+}
+
+void Semaphore::WaitForWake()
+{
+  AppleSemaphore *sem = (AppleSemaphore *)this;
+  // no timeout, so no point checking return value as that's the only failure case
+  dispatch_semaphore_wait(sem->h, DISPATCH_TIME_FOREVER);
+}
+
+Semaphore::Semaphore()
+{
+}
+
+Semaphore::~Semaphore()
+{
+}
+
+};
diff --git a/renderdoc/os/posix/linux/linux_threading.cpp b/renderdoc/os/posix/linux/linux_threading.cpp
index 3f3c280fd..ce6b7f806 100644
--- a/renderdoc/os/posix/linux/linux_threading.cpp
+++ b/renderdoc/os/posix/linux/linux_threading.cpp
@@ -24,6 +24,10 @@
 
 #include "os/os_specific.h"
 
+#include "common/common.h"
+
+#include <errno.h>
+#include <semaphore.h>
 #include <sys/prctl.h>
 #include <time.h>
 #include <unistd.h>
@@ -44,3 +48,67 @@ void Threading::SetCurrentThreadName(const rdcstr &name)
 {
   prctl(PR_SET_NAME, (unsigned long)name.c_str(), 0, 0, 0);
 }
+
+namespace Threading
+{
+
+// works for all posix except apple, hence being here
+struct PosixSemaphore : public Semaphore
+{
+  ~PosixSemaphore() {}
+
+  sem_t h;
+};
+
+Semaphore *Semaphore::Create()
+{
+  PosixSemaphore *sem = new PosixSemaphore();
+  int err = sem_init(&sem->h, 0, 0);
+  // only documented errors are too large initial value (impossible for 0) or for shared semaphores
+  // going wrong (we're not shared)
+  RDCASSERT(err == 0, errno);
+  return sem;
+}
+
+void Semaphore::Destroy()
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+  sem_destroy(&sem->h);
+  delete sem;
+}
+
+void Semaphore::Wake(uint32_t numToWake)
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+  for(uint32_t i = 0; i < numToWake; i++)
+    sem_post(&sem->h);
+}
+
+void Semaphore::WaitForWake()
+{
+  PosixSemaphore *sem = (PosixSemaphore *)this;
+
+  // handle extremely moronic stupid signal interruptions
+  do
+  {
+    int ret = sem_wait(&sem->h);
+
+    if(ret == -1)
+    {
+      if(errno == EINTR)
+        continue;
+
+      RDCWARN("Semaphore wait failed: %d", errno);
+    }
+  } while(false);
+}
+
+Semaphore::Semaphore()
+{
+}
+
+Semaphore::~Semaphore()
+{
+}
+
+};
diff --git a/renderdoc/os/win32/win32_threading.cpp b/renderdoc/os/win32/win32_threading.cpp
index b99f0346d..a8b15d317 100644
--- a/renderdoc/os/win32/win32_threading.cpp
+++ b/renderdoc/os/win32/win32_threading.cpp
@@ -368,4 +368,48 @@ void Sleep(uint32_t milliseconds)
 {
   ::Sleep((DWORD)milliseconds);
 }
+
+struct Win32Semaphore : public Semaphore
+{
+  ~Win32Semaphore() {}
+
+  HANDLE h;
+};
+
+Semaphore *Semaphore::Create()
+{
+  Win32Semaphore *sem = new Win32Semaphore();
+  sem->h = CreateSemaphore(NULL, 0, 0xffff, NULL);
+  return sem;
+}
+
+void Semaphore::Destroy()
+{
+  Win32Semaphore *sem = (Win32Semaphore *)this;
+  CloseHandle(sem->h);
+  delete sem;
+}
+
+void Semaphore::Wake(uint32_t numToWake)
+{
+  Win32Semaphore *sem = (Win32Semaphore *)this;
+  ReleaseSemaphore(sem->h, numToWake, NULL);
+}
+
+void Semaphore::WaitForWake()
+{
+  Win32Semaphore *sem = (Win32Semaphore *)this;
+  DWORD err = WaitForSingleObject(sem->h, INFINITE);
+  if(err == WAIT_FAILED)
+    RDCWARN("Semaphore failed to sleep: %d", GetLastError());
+}
+
+Semaphore::Semaphore()
+{
+}
+
+Semaphore::~Semaphore()
+{
+}
+
 };