--- dyld/dyld-750.5/dyld3/APIs_macOS.cpp
+++ dyld/dyld-655.1/dyld3/APIs_macOS.cpp
@@ -33,12 +33,11 @@
 #include <fcntl.h>
 #include <TargetConditionals.h>
 #include <malloc/malloc.h>
-#include <mach-o/dyld_priv.h>
-#include <mach-o/dyld_images.h>
 
 #include <algorithm>
 
 #include "dlfcn.h"
+#include "dyld_priv.h"
 
 #include "AllImages.h"
 #include "Loading.h"
@@ -98,13 +97,19 @@
     bool usable = false;
     const MachOFile* mf = (MachOFile*)memImage;
     if ( mf->hasMachOMagic() && mf->isMachO(diag, memImageSize) ) {
-        usable = (gAllImages.archs().grade(mf->cputype, mf->cpusubtype) != 0);
+        if ( strcmp(mf->archName(), MachOFile::currentArchName()) == 0 )
+            usable = true;
+#if __x86_64__
+        // <rdar://problem/42727628> support thin x86_64 on haswell machines
+        else if ( (strcmp(MachOFile::currentArchName(), "x86_64h") == 0) && (strcmp(mf->archName(), "x86_64") == 0) )
+            usable = true;
+#endif
     }
     else if ( const FatFile* ff = FatFile::isFatFile(memImage) ) {
         uint64_t sliceOffset;
         uint64_t sliceLen;
         bool     missingSlice;
-        if ( ff->isFatFileWithSlice(diag, memImageSize, gAllImages.archs(), sliceOffset, sliceLen, missingSlice) ) {
+        if ( ff->isFatFileWithSlice(diag, memImageSize, MachOFile::currentArchName(), sliceOffset, sliceLen, missingSlice) ) {
             mf = (MachOFile*)((long)memImage+sliceOffset);
             if ( mf->isMachO(diag, sliceLen) ) {
                 usable = true;
@@ -150,27 +155,24 @@
         // if this is memory based image, write to temp file, then use file based loading
         if ( image.memSource != nullptr ) {
             // make temp file with content of memory buffer
-            image.path = nullptr;
-            char tempFileName[PATH_MAX];
-            const char* tmpDir = getenv("TMPDIR");
-            if ( (tmpDir != nullptr) && (strlen(tmpDir) > 2) ) {
-                strlcpy(tempFileName, tmpDir, PATH_MAX);
-                if ( tmpDir[strlen(tmpDir)-1] != '/' )
-                    strlcat(tempFileName, "/", PATH_MAX);
+            bool successfullyWritten = false;
+            image.path = ::tempnam(nullptr, "NSCreateObjectFileImageFromMemory-");
+            if ( image.path != nullptr ) {
+                int fd = ::open(image.path, O_WRONLY | O_CREAT | O_EXCL, 0644);
+                if ( fd != -1 ) {
+                    ssize_t writtenSize = ::pwrite(fd, image.memSource, image.memLength, 0);
+                    if ( writtenSize == image.memLength )
+                        successfullyWritten = true;
+                    ::close(fd);
+                }
             }
-            else
-                strlcpy(tempFileName,"/tmp/", PATH_MAX);
-            strlcat(tempFileName, "NSCreateObjectFileImageFromMemory-XXXXXXXX", PATH_MAX);
-            int fd = ::mkstemp(tempFileName);
-            if ( fd != -1 ) {
-                ssize_t writtenSize = ::pwrite(fd, image.memSource, image.memLength, 0);
-                if ( writtenSize == image.memLength ) {
-                    image.path = strdup(tempFileName);
+            if ( !successfullyWritten ) {
+                if ( image.path != nullptr ) {
+                    free((void*)image.path);
+                    image.path = nullptr;
                 }
-                else {
-                    log_apis("NSLinkModule() => NULL (could not save memory image to temp file)\n");
-                }
-                ::close(fd);
+                log_apis("NSLinkModule() => NULL (could not save memory image to temp file)\n");
+                return;
             }
         }
         path = image.path;
@@ -188,7 +190,7 @@
     // dlopen the binary outside of the read lock as we don't want to risk deadlock
     Diagnostics diag;
     void* callerAddress = __builtin_return_address(1); // note layers: 1: real client, 0: libSystem glue
-    const MachOLoaded* loadAddress = gAllImages.dlopen(diag, path, false, false, false, false, true, callerAddress);
+    const MachOLoaded* loadAddress = gAllImages.dlopen(diag, path, false, false, false, true, callerAddress);
     if ( diag.hasError() ) {
         log_apis("   NSLinkModule: failed: %s\n", diag.errorMessage());
         return nullptr;