diff --git a/dlls/kernel32/kernel32.spec b/dlls/kernel32/kernel32.spec
index 1a18899d6c3..6fb14bbcbf4 100644
--- a/dlls/kernel32/kernel32.spec
+++ b/dlls/kernel32/kernel32.spec
@@ -712,6 +712,7 @@
 @ stdcall InitAtomTable(long)
 @ stdcall InitializeCriticalSection(ptr)
 @ stdcall InitializeCriticalSectionAndSpinCount(ptr long)
+@ stdcall InitializeCriticalSectionEx(ptr long long)
 @ stdcall InitializeSListHead(ptr) ntdll.RtlInitializeSListHead
 @ stdcall InterlockedCompareExchange (ptr long long)
 @ stdcall InterlockedDecrement(ptr)
diff --git a/dlls/kernel32/sync.c b/dlls/kernel32/sync.c
index 0032d17ef92..da558fd63d3 100644
--- a/dlls/kernel32/sync.c
+++ b/dlls/kernel32/sync.c
@@ -350,8 +350,7 @@ DWORD WINAPI SignalObjectAndWait( HANDLE hObjectToSignal, HANDLE hObjectToWaitOn
  */
 void WINAPI InitializeCriticalSection( CRITICAL_SECTION *crit )
 {
-    NTSTATUS ret = RtlInitializeCriticalSection( crit );
-    if (ret) RtlRaiseStatus( ret );
+    InitializeCriticalSectionEx( crit, 0, 0 );
 }
 
 /***********************************************************************
@@ -372,7 +371,29 @@ void WINAPI InitializeCriticalSection( CRITICAL_SECTION *crit )
  */
 BOOL WINAPI InitializeCriticalSectionAndSpinCount( CRITICAL_SECTION *crit, DWORD spincount )
 {
-    NTSTATUS ret = RtlInitializeCriticalSectionAndSpinCount( crit, spincount );
+    return InitializeCriticalSectionEx( crit, spincount, 0 );
+}
+
+/***********************************************************************
+ *           InitializeCriticalSectionEx   (KERNEL32.@)
+ *
+ * Initialise a critical section with a spin count and flags.
+ *
+ * PARAMS
+ *  crit      [O] Critical section to initialise.
+ *  spincount [I] Number of times to spin upon contention.
+ *  flags     [I] CRITICAL_SECTION_ flags from winbase.h.
+ *
+ * RETURNS
+ *  Success: TRUE.
+ *  Failure: Nothing. If the function fails an exception is raised.
+ *
+ * NOTES
+ *  spincount is ignored on uni-processor systems.
+ */
+BOOL WINAPI InitializeCriticalSectionEx( CRITICAL_SECTION *crit, DWORD spincount, DWORD flags )
+{
+    NTSTATUS ret = RtlInitializeCriticalSectionEx( crit, spincount, flags );
     if (ret) RtlRaiseStatus( ret );
     return !ret;
 }
diff --git a/dlls/ntdll/critsection.c b/dlls/ntdll/critsection.c
index 0fa47c49bce..284634353b4 100644
--- a/dlls/ntdll/critsection.c
+++ b/dlls/ntdll/critsection.c
@@ -247,13 +247,14 @@ static inline NTSTATUS wait_semaphore( RTL_CRITICAL_SECTION *crit, int timeout )
  *  STATUS_SUCCESS.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSectionAndSpinCount(), RtlDeleteCriticalSection(),
  *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
  *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
  */
 NTSTATUS WINAPI RtlInitializeCriticalSection( RTL_CRITICAL_SECTION *crit )
 {
-    return RtlInitializeCriticalSectionAndSpinCount( crit, 0 );
+    return RtlInitializeCriticalSectionEx( crit, 0, 0 );
 }
 
 /***********************************************************************
@@ -272,13 +273,53 @@ NTSTATUS WINAPI RtlInitializeCriticalSection( RTL_CRITICAL_SECTION *crit )
  *  Available on NT4 SP3 or later.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlDeleteCriticalSection(),
  *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
  *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
  */
 NTSTATUS WINAPI RtlInitializeCriticalSectionAndSpinCount( RTL_CRITICAL_SECTION *crit, ULONG spincount )
 {
-    crit->DebugInfo = RtlAllocateHeap(GetProcessHeap(), 0, sizeof(RTL_CRITICAL_SECTION_DEBUG));
+    return RtlInitializeCriticalSectionEx( crit, spincount, 0 );
+}
+
+/***********************************************************************
+ *           RtlInitializeCriticalSectionEx   (NTDLL.@)
+ *
+ * Initialises a new critical section with a given spin count and flags.
+ *
+ * PARAMS
+ *   crit      [O] Critical section to initialise.
+ *   spincount [I] Number of times to spin upon contention.
+ *   flags     [I] RTL_CRITICAL_SECTION_FLAG_ flags from winnt.h.
+ *
+ * RETURNS
+ *  STATUS_SUCCESS.
+ *
+ * NOTES
+ *  Available on Vista or later.
+ *
+ * SEE
+ *  RtlInitializeCriticalSection(), RtlDeleteCriticalSection(),
+ *  RtlEnterCriticalSection(), RtlLeaveCriticalSection(),
+ *  RtlTryEnterCriticalSection(), RtlSetCriticalSectionSpinCount()
+ */
+NTSTATUS WINAPI RtlInitializeCriticalSectionEx( RTL_CRITICAL_SECTION *crit, ULONG spincount, ULONG flags )
+{
+    if (flags & (RTL_CRITICAL_SECTION_FLAG_DYNAMIC_SPIN|RTL_CRITICAL_SECTION_FLAG_STATIC_INIT))
+        FIXME("(%p,%u,0x%08x) semi-stub\n", crit, spincount, flags);
+
+    /* FIXME: if RTL_CRITICAL_SECTION_FLAG_STATIC_INIT is given, we should use
+     * memory from a static pool to hold the debug info. Then heap.c could pass
+     * this flag rather than initialising the process heap CS by hand. If this
+     * is done, then debug info should be managed through Rtlp[Allocate|Free]DebugInfo
+     * so (e.g.) MakeCriticalSectionGlobal() doesn't free it using HeapFree().
+     */
+    if (flags & RTL_CRITICAL_SECTION_FLAG_NO_DEBUG_INFO)
+        crit->DebugInfo = NULL;
+    else
+        crit->DebugInfo = RtlAllocateHeap(GetProcessHeap(), 0, sizeof(RTL_CRITICAL_SECTION_DEBUG));
+
     if (crit->DebugInfo)
     {
         crit->DebugInfo->Type = 0;
@@ -315,6 +356,7 @@ NTSTATUS WINAPI RtlInitializeCriticalSectionAndSpinCount( RTL_CRITICAL_SECTION *
  *  If the system is not SMP, spincount is ignored and set to 0.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
@@ -339,6 +381,7 @@ ULONG WINAPI RtlSetCriticalSectionSpinCount( RTL_CRITICAL_SECTION *crit, ULONG s
  *  STATUS_SUCCESS.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
@@ -380,6 +423,7 @@ NTSTATUS WINAPI RtlDeleteCriticalSection( RTL_CRITICAL_SECTION *crit )
  *  faster.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
@@ -442,6 +486,7 @@ NTSTATUS WINAPI RtlpWaitForCriticalSection( RTL_CRITICAL_SECTION *crit )
  *  faster.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
@@ -473,6 +518,7 @@ NTSTATUS WINAPI RtlpUnWaitCriticalSection( RTL_CRITICAL_SECTION *crit )
  *  STATUS_SUCCESS. The critical section is held by the caller.
  *  
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlSetCriticalSectionSpinCount(),
  *  RtlLeaveCriticalSection(), RtlTryEnterCriticalSection()
@@ -526,6 +572,7 @@ done:
  *  Failure: FALSE. The critical section is currently held by another thread.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlLeaveCriticalSection(), RtlSetCriticalSectionSpinCount()
@@ -561,6 +608,7 @@ BOOL WINAPI RtlTryEnterCriticalSection( RTL_CRITICAL_SECTION *crit )
  *  STATUS_SUCCESS.
  *
  * SEE
+ *  RtlInitializeCriticalSectionEx(),
  *  RtlInitializeCriticalSection(), RtlInitializeCriticalSectionAndSpinCount(),
  *  RtlDeleteCriticalSection(), RtlEnterCriticalSection(),
  *  RtlSetCriticalSectionSpinCount(), RtlTryEnterCriticalSection()
diff --git a/dlls/ntdll/ntdll.spec b/dlls/ntdll/ntdll.spec
index ed89cbd4b36..575f99da373 100644
--- a/dlls/ntdll/ntdll.spec
+++ b/dlls/ntdll/ntdll.spec
@@ -664,6 +664,7 @@
 @ stub RtlInitializeContext
 @ stdcall RtlInitializeCriticalSection(ptr)
 @ stdcall RtlInitializeCriticalSectionAndSpinCount(ptr long)
+@ stdcall RtlInitializeCriticalSectionEx(ptr long long)
 @ stdcall RtlInitializeGenericTable(ptr ptr ptr ptr ptr)
 # @ stub RtlInitializeGenericTableAvl
 @ stdcall RtlInitializeHandleTable(long long ptr)
diff --git a/include/winbase.h b/include/winbase.h
index 433b98510d6..c47a1a500fe 100644
--- a/include/winbase.h
+++ b/include/winbase.h
@@ -54,6 +54,8 @@ typedef RTL_CRITICAL_SECTION_DEBUG CRITICAL_SECTION_DEBUG;
 typedef PRTL_CRITICAL_SECTION_DEBUG PCRITICAL_SECTION_DEBUG;
 typedef PRTL_CRITICAL_SECTION_DEBUG LPCRITICAL_SECTION_DEBUG;
 
+#define CRITICAL_SECTION_NO_DEBUG_INFO RTL_CRITICAL_SECTION_FLAG_NO_DEBUG_INFO
+
 typedef WAITORTIMERCALLBACKFUNC WAITORTIMERCALLBACK;
 
 #define EXCEPTION_DEBUG_EVENT       1
@@ -1777,6 +1779,7 @@ WINBASEAPI BOOL        WINAPI InitAtomTable(DWORD);
 WINADVAPI  BOOL        WINAPI InitializeAcl(PACL,DWORD,DWORD);
 WINBASEAPI void        WINAPI InitializeCriticalSection(CRITICAL_SECTION *lpCrit);
 WINBASEAPI BOOL        WINAPI InitializeCriticalSectionAndSpinCount(CRITICAL_SECTION *,DWORD);
+WINBASEAPI BOOL        WINAPI InitializeCriticalSectionEx(CRITICAL_SECTION *,DWORD,DWORD);
 WINADVAPI  BOOL        WINAPI InitializeSecurityDescriptor(PSECURITY_DESCRIPTOR,DWORD);
 WINADVAPI  BOOL        WINAPI InitializeSid(PSID,PSID_IDENTIFIER_AUTHORITY,BYTE);
 WINBASEAPI VOID        WINAPI InitializeSListHead(PSLIST_HEADER);
diff --git a/include/winnt.h b/include/winnt.h
index 70853638855..f9ae9d4a4a5 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -4700,6 +4700,12 @@ typedef struct _RTL_CRITICAL_SECTION {
     ULONG_PTR SpinCount;
 }  RTL_CRITICAL_SECTION, *PRTL_CRITICAL_SECTION;
 
+#define RTL_CRITICAL_SECTION_FLAG_NO_DEBUG_INFO 0x1000000
+#define RTL_CRITICAL_SECTION_FLAG_DYNAMIC_SPIN  0x2000000
+#define RTL_CRITICAL_SECTION_FLAG_STATIC_INIT   0x4000000
+#define RTL_CRITICAL_SECTION_ALL_FLAG_BITS      0xFF000000
+#define RTL_CRITICAL_SECTION_FLAG_RESERVED      (RTL_CRITICAL_SECTION_ALL_FLAG_BITS & ~0x7000000)
+
 typedef VOID (NTAPI * WAITORTIMERCALLBACKFUNC) (PVOID, BOOLEAN );
 typedef VOID (NTAPI * PFLS_CALLBACK_FUNCTION) ( PVOID );
 
diff --git a/include/winternl.h b/include/winternl.h
index 39339c2b77a..fe2f83d3feb 100644
--- a/include/winternl.h
+++ b/include/winternl.h
@@ -2219,7 +2219,8 @@ NTSYSAPI NTSTATUS  WINAPI RtlInitAnsiStringEx(PANSI_STRING,PCSZ);
 NTSYSAPI void      WINAPI RtlInitUnicodeString(PUNICODE_STRING,PCWSTR);
 NTSYSAPI NTSTATUS  WINAPI RtlInitUnicodeStringEx(PUNICODE_STRING,PCWSTR);
 NTSYSAPI NTSTATUS  WINAPI RtlInitializeCriticalSection(RTL_CRITICAL_SECTION *);
-NTSYSAPI NTSTATUS  WINAPI RtlInitializeCriticalSectionAndSpinCount(RTL_CRITICAL_SECTION *,DWORD);
+NTSYSAPI NTSTATUS  WINAPI RtlInitializeCriticalSectionAndSpinCount(RTL_CRITICAL_SECTION *,ULONG);
+NTSYSAPI NTSTATUS  WINAPI RtlInitializeCriticalSectionEx(RTL_CRITICAL_SECTION *,ULONG,ULONG);
 NTSYSAPI void      WINAPI RtlInitializeBitMap(PRTL_BITMAP,PULONG,ULONG);
 NTSYSAPI void      WINAPI RtlInitializeHandleTable(ULONG,ULONG,RTL_HANDLE_TABLE *);
 NTSYSAPI void      WINAPI RtlInitializeResource(LPRTL_RWLOCK);