diff --git a/src/corelib/global/qlogging_p.h b/src/corelib/global/qlogging_p.h
index bc331c80c0d..9122524f8b1 100644
--- a/src/corelib/global/qlogging_p.h
+++ b/src/corelib/global/qlogging_p.h
@@ -17,7 +17,7 @@
 
 #include <QtCore/private/qglobal_p.h>
 #include "qlogging.h"
-#include "qloggingcategory.h"
+#include <QtCore/qloggingcategory.h>
 
 #if !defined(QT_BOOTSTRAPPED) && QT_CONFIG(regularexpression)
 #  if __has_include(<cxxabi.h>) && QT_CONFIG(backtrace)
diff --git a/src/corelib/global/qsimd.cpp b/src/corelib/global/qsimd.cpp
index 15755b1ca22..732ce3cf30c 100644
--- a/src/corelib/global/qsimd.cpp
+++ b/src/corelib/global/qsimd.cpp
@@ -252,7 +252,7 @@ static inline quint64 detectProcessorFeatures()
 # define X86_BASELINE   "no-sse"
 #endif
 
-#if defined(Q_CC_GNU)
+#if defined(Q_CC_GNU) || defined(Q_CC_CLANG)
 // lower the target for functions in this file
 #  undef QT_FUNCTION_TARGET_BASELINE
 #  define QT_FUNCTION_TARGET_BASELINE               __attribute__((target(X86_BASELINE)))
diff --git a/src/corelib/global/qsimd_p.h b/src/corelib/global/qsimd_p.h
index 233c7a3167a..6723c78ff44 100644
--- a/src/corelib/global/qsimd_p.h
+++ b/src/corelib/global/qsimd_p.h
@@ -101,7 +101,7 @@ QT_WARNING_DISABLE_INTEL(103)
 
 #if defined(Q_PROCESSOR_ARM_64)
 #  define QT_COMPILER_SUPPORTS_HERE(x)    ((__ARM_FEATURE_ ## x) || (__ ## x ## __) || QT_COMPILER_SUPPORTS(x))
-#  if defined(Q_CC_GNU)
+#  if defined(Q_CC_GNU) || defined(Q_CC_CLANG)
      /* GCC requires attributes for a function */
 #    define QT_FUNCTION_TARGET(x)  __attribute__((__target__(QT_FUNCTION_TARGET_STRING_ ## x)))
 #  else
@@ -124,12 +124,12 @@ QT_WARNING_DISABLE_INTEL(103)
 #  define QT_COMPILER_SUPPORTS_HERE(x)    QT_COMPILER_SUPPORTS(x)
 #  define QT_FUNCTION_TARGET(x)
 #elif defined(Q_PROCESSOR_X86)
-#  if defined(Q_CC_CLANG) && defined(Q_CC_MSVC)
+#  if defined(Q_CC_CLANG) && defined(Q_CC_MSVC) && (Q_CC_CLANG < 1900)
 #    define QT_COMPILER_SUPPORTS_HERE(x)    (__ ## x ## __)
 #  else
 #    define QT_COMPILER_SUPPORTS_HERE(x)    ((__ ## x ## __) || QT_COMPILER_SUPPORTS(x))
 #  endif
-#  if defined(Q_CC_GNU)
+#  if defined(Q_CC_GNU) || defined(Q_CC_CLANG)
      /* GCC requires attributes for a function */
 #    define QT_FUNCTION_TARGET(x)  __attribute__((__target__(QT_FUNCTION_TARGET_STRING_ ## x)))
 #  else
diff --git a/src/corelib/global/qsystemdetection.h b/src/corelib/global/qsystemdetection.h
index 0cbcef27407..bd1ef8dd747 100644
--- a/src/corelib/global/qsystemdetection.h
+++ b/src/corelib/global/qsystemdetection.h
@@ -242,7 +242,8 @@
 #if defined(__SIZEOF_INT128__)
 // Compiler used in VxWorks SDK declares __SIZEOF_INT128__ but VxWorks doesn't support this type,
 // so we can't rely solely on compiler here.
-#if !defined(Q_OS_VXWORKS)
+// MSVC STL used by MSVC and clang-cl does not support int128
+#if !defined(Q_OS_VXWORKS) && !defined(_MSC_VER)
 #  define QT_COMPILER_SUPPORTS_INT128 __SIZEOF_INT128__
 #endif
 #endif // defined(__SIZEOF_INT128__)