diff --git a/third_party/libopenjpeg20/opj_malloc.h b/third_party/libopenjpeg20/opj_malloc.h
index cbc4106c7..79b3a6410 100644
--- a/third_party/libopenjpeg20/opj_malloc.h
+++ b/third_party/libopenjpeg20/opj_malloc.h
@@ -31,8 +31,6 @@
  */
 #ifndef OPJ_MALLOC_H
 #define OPJ_MALLOC_H
-
-#include <stddef.h>
 /**
 @file opj_malloc.h
 @brief Internal functions
@@ -52,7 +50,16 @@ Allocate an uninitialized memory block
 @param size Bytes to allocate
 @return Returns a void pointer to the allocated space, or NULL if there is insufficient memory available
 */
-void * opj_malloc(size_t size);
+#ifdef ALLOC_PERF_OPT
+void * OPJ_CALLCONV opj_malloc(size_t size);
+#else
+/* prevent assertion on overflow for MSVC */
+#ifdef _MSC_VER
+#define opj_malloc(size) ((size_t)(size) >= (size_t)-0x100 ? NULL : malloc(size))
+#else
+#define opj_malloc(size) malloc(size)
+#endif
+#endif
 
 /**
 Allocate a memory block with elements initialized to 0
@@ -60,24 +67,98 @@ Allocate a memory block with elements initialized to 0
 @param sizeOfElements Bytes per block to allocate
 @return Returns a void pointer to the allocated space, or NULL if there is insufficient memory available
 */
-void * opj_calloc(size_t numOfElements, size_t sizeOfElements);
+#ifdef ALLOC_PERF_OPT
+void * OPJ_CALLCONV opj_calloc(size_t _NumOfElements, size_t _SizeOfElements);
+#else
+/* prevent assertion on overflow for MSVC */
+#ifdef _MSC_VER
+#define opj_calloc(num, size) ((size_t)(num) != 0 && (size_t)(num) >= (size_t)-0x100 / (size_t)(size) ? NULL : calloc(num, size))
+#else
+#define opj_calloc(num, size) calloc(num, size)
+#endif
+#endif
 
 /**
 Allocate memory aligned to a 16 byte boundary
 @param size Bytes to allocate
 @return Returns a void pointer to the allocated space, or NULL if there is insufficient memory available
 */
-void * opj_aligned_malloc(size_t size);
-void * opj_aligned_realloc(void *ptr, size_t size);
-void opj_aligned_free(void* ptr);
+/* FIXME: These should be set with cmake tests, but we're currently not requiring use of cmake */
+#ifdef _WIN32
+  /* Someone should tell the mingw people that their malloc.h ought to provide _mm_malloc() */
+  #ifdef __GNUC__
+    #include <mm_malloc.h>
+    #define HAVE_MM_MALLOC
+  #else /* MSVC, Intel C++ */
+    #include <malloc.h>
+    #ifdef _mm_malloc
+      #define HAVE_MM_MALLOC
+    #endif
+  #endif
+#else /* Not _WIN32 */
+  #if defined(__sun)
+    #define HAVE_MEMALIGN
+  #elif defined(__FreeBSD__)
+    #define HAVE_POSIX_MEMALIGN
+  /* Linux x86_64 and OSX always align allocations to 16 bytes */
+  #elif !defined(__amd64__) && !defined(__APPLE__) && !defined(_AIX)
+    #define HAVE_MEMALIGN
+    #include <malloc.h>
+  #endif
+#endif
 
-/**
-Allocate memory aligned to a 32 byte boundary
-@param size Bytes to allocate
-@return Returns a void pointer to the allocated space, or NULL if there is insufficient memory available
-*/
-void * opj_aligned_32_malloc(size_t size);
-void * opj_aligned_32_realloc(void *ptr, size_t size);
+#define opj_aligned_malloc(size) malloc(size)
+#define opj_aligned_32_malloc(size) malloc(size)
+#define opj_aligned_free(m) free(m)
+
+#ifdef HAVE_MM_MALLOC
+  #undef opj_aligned_malloc
+  #define opj_aligned_malloc(size) _mm_malloc((size), 16)
+  #undef opj_aligned_32_malloc
+  #define opj_aligned_32_malloc(size) _mm_malloc((size), 32)
+  #undef opj_aligned_free
+  #define opj_aligned_free(m) _mm_free(m)
+#endif
+
+#ifdef HAVE_MEMALIGN
+  extern void* memalign(size_t, size_t);
+  #undef opj_aligned_malloc
+  #define opj_aligned_malloc(size) memalign(16, (size))
+  #undef opj_aligned_32_malloc
+  #define opj_aligned_32_malloc(size) memalign(32, (size))
+  #undef opj_aligned_free
+  #define opj_aligned_free(m) free(m)
+#endif
+
+#ifdef HAVE_POSIX_MEMALIGN
+  #undef opj_aligned_malloc
+  extern int posix_memalign(void**, size_t, size_t);
+
+  static INLINE void* __attribute__ ((malloc)) opj_aligned_malloc(size_t size){
+    void* mem = NULL;
+    posix_memalign(&mem, 16, size);
+    return mem;
+  }
+
+  #undef opj_aligned_32_malloc
+  static INLINE void* __attribute__ ((malloc)) opj_aligned_32_malloc(size_t size){
+    void* mem = NULL;
+    posix_memalign(&mem, 32, size);
+    return mem;
+  }
+
+  #undef opj_aligned_free
+  #define opj_aligned_free(m) free(m)
+#endif
+
+#ifdef ALLOC_PERF_OPT
+  #undef opj_aligned_malloc
+  #define opj_aligned_malloc(size) opj_malloc(size)
+  #undef opj_aligned_32_malloc
+  #define opj_aligned_32_malloc(size) opj_malloc(size)
+  #undef opj_aligned_free
+  #define opj_aligned_free(m) opj_free(m)
+#endif
 
 /**
 Reallocate memory blocks.
@@ -85,13 +166,26 @@ Reallocate memory blocks.
 @param s New size in bytes
 @return Returns a void pointer to the reallocated (and possibly moved) memory block
 */
-void * opj_realloc(void * m, size_t s);
+#ifdef ALLOC_PERF_OPT
+void * OPJ_CALLCONV opj_realloc(void * m, size_t s);
+#else
+/* prevent assertion on overflow for MSVC */
+#ifdef _MSC_VER
+#define opj_realloc(m, s) ((size_t)(s) >= (size_t)-0x100 ? NULL : realloc(m, s))
+#else
+#define opj_realloc(m, s) realloc(m, s)
+#endif
+#endif
 
 /**
 Deallocates or frees a memory block.
 @param m Previously allocated memory block to be freed
 */
-void opj_free(void * m);
+#ifdef ALLOC_PERF_OPT
+void OPJ_CALLCONV opj_free(void * m);
+#else
+#define opj_free(m) free(m)
+#endif
 
 #if defined(__GNUC__) && !defined(OPJ_SKIP_POISON)
 #pragma GCC poison malloc calloc realloc free