diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_file.h b/compiler-rt/lib/sanitizer_common/sanitizer_file.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_file.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_file.h
@@ -78,6 +78,7 @@
 // OS
 const char *GetPwd();
 bool FileExists(const char *filename);
+bool DirExists(const char *path);
 char *FindPathToBinary(const char *name);
 bool IsPathSeparator(const char c);
 bool IsAbsolutePath(const char *path);
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_file.cpp
@@ -83,8 +83,14 @@
     if (!IsPathSeparator(path[i]))
       continue;
     path[i] = '\0';
-    /* Some of these will fail, because the directory exists, ignore it. */
-    CreateDir(path);
+    if (!DirExists(path)) {
+      if (!CreateDir(path)) {
+        const char *ErrorMsgPrefix = "ERROR: Can't create directory: ";
+        WriteToFile(kStderrFd, ErrorMsgPrefix, internal_strlen(ErrorMsgPrefix));
+        WriteToFile(kStderrFd, path, internal_strlen(path));
+        Die();
+      }
+    }
     path[i] = save;
   }
 }
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -499,6 +499,17 @@
   return S_ISREG(st.st_mode);
 }
 
+bool DirExists(const char *path) {
+  struct stat st;
+#if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
+  if (internal_syscall(SYSCALL(newfstatat), AT_FDCWD, path, &st, 0))
+#else
+  if (internal_stat(path, &st))
+#endif
+    return false;
+  return S_ISDIR(st.st_mode);
+}
+
 #if !SANITIZER_NETBSD
 tid_t GetTid() {
 #if SANITIZER_FREEBSD
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
@@ -392,6 +392,13 @@
   return S_ISREG(st.st_mode);
 }
 
+bool DirExists(const char *path) {
+  struct stat st;
+  if (stat(path, &st))
+    return false;
+  return S_ISDIR(st.st_mode);
+}
+
 tid_t GetTid() {
   tid_t tid;
   pthread_threadid_np(nullptr, &tid);
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
--- a/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_win.cpp
@@ -93,6 +93,11 @@
   return ::GetFileAttributesA(filename) != INVALID_FILE_ATTRIBUTES;
 }
 
+bool DirExists(const char *path) {
+  auto attr = ::GetFileAttributesA(path);
+  return (attr != INVALID_FILE_ATTRIBUTES) && (attr & FILE_ATTRIBUTE_DIRECTORY);
+}
+
 uptr internal_getpid() {
   return GetProcessId(GetCurrentProcess());
 }
diff --git a/compiler-rt/test/asan/TestCases/log-path_test.cpp b/compiler-rt/test/asan/TestCases/log-path_test.cpp
--- a/compiler-rt/test/asan/TestCases/log-path_test.cpp
+++ b/compiler-rt/test/asan/TestCases/log-path_test.cpp
@@ -16,10 +16,14 @@
 // RUN: %env_asan_opts=log_path=%t.log not %run %t 2> %t.out
 // RUN: FileCheck %s --check-prefix=CHECK-ERROR < %t.log.*
 
-// Invalid log_path.
-// RUN: %env_asan_opts=log_path=/dev/null/INVALID not %run %t 2> %t.out
+// Invalid log_path in existing directory.
+// RUN: %env_asan_opts=log_path=/INVALID not %run %t 2> %t.out
 // RUN: FileCheck %s --check-prefix=CHECK-INVALID < %t.out
 
+// Directory of log_path can't be created.
+// RUN: %env_asan_opts=log_path=/dev/null/INVALID not %run %t 2> %t.out
+// RUN: FileCheck %s --check-prefix=CHECK-BAD-DIR < %t.out
+
 // Too long log_path.
 // RUN: %env_asan_opts=log_path=`for((i=0;i<10000;i++)); do echo -n $i; done` \
 // RUN:   not %run %t 2> %t.out
@@ -44,5 +48,6 @@
   return res;
 }
 // CHECK-ERROR: ERROR: AddressSanitizer
-// CHECK-INVALID: ERROR: Can't open file: /dev/null/INVALID
+// CHECK-INVALID: ERROR: Can't open file: /INVALID
+// CHECK-BAD-DIR: ERROR: Can't create directory: /dev/null
 // CHECK-LONG: ERROR: Path is too long: 01234
diff --git a/compiler-rt/test/memprof/TestCases/log_path_test.cpp b/compiler-rt/test/memprof/TestCases/log_path_test.cpp
--- a/compiler-rt/test/memprof/TestCases/log_path_test.cpp
+++ b/compiler-rt/test/memprof/TestCases/log_path_test.cpp
@@ -3,18 +3,21 @@
 //
 // RUN: %clangxx_memprof  %s -o %t
 
-// stderr print_text=true:log_path
+// stderr log_path
 // RUN: %env_memprof_opts=print_text=true:log_path=stderr %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-GOOD --dump-input=always
 
-// Good print_text=true:log_path.
+// Good log_path.
 // RUN: rm -f %t.log.*
 // RUN: %env_memprof_opts=print_text=true:log_path=%t.log %run %t
 // RUN: FileCheck %s --check-prefix=CHECK-GOOD --dump-input=always < %t.log.*
 
-// Invalid print_text=true:log_path.
-// RUN: %env_memprof_opts=print_text=true:log_path=/dev/null/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
+// Invalid log_path.
+// RUN: %env_memprof_opts=print_text=true:log_path=/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
 
-// Too long print_text=true:log_path.
+// Directory of log_path can't be created.
+// RUN: %env_memprof_opts=print_text=true:log_path=/dev/null/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-BAD-DIR --dump-input=always
+
+// Too long log_path.
 // RUN: %env_memprof_opts=print_text=true:log_path=`for((i=0;i<10000;i++)); do echo -n $i; done` \
 // RUN:   not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-LONG --dump-input=always
 
@@ -24,7 +27,7 @@
 // Using an automatically generated name via %t can cause weird issues with
 // unexpected macro expansion if the path includes tokens that match a build
 // system macro (e.g. "linux").
-// RUN: %clangxx_memprof  %s -o %t -DPROFILE_NAME_VAR="/dev/null/INVALID"
+// RUN: %clangxx_memprof  %s -o %t -DPROFILE_NAME_VAR="/INVALID"
 // RUN: not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
 
 #include <sanitizer/memprof_interface.h>
@@ -45,5 +48,6 @@
   return 0;
 }
 // CHECK-GOOD: Memory allocation stack id
-// CHECK-INVALID: ERROR: Can't open file: /dev/null/INVALID
+// CHECK-INVALID: ERROR: Can't open file: /INVALID
+// CHECK-BAD-DIR: ERROR: Can't create directory: /dev/null
 // CHECK-LONG: ERROR: Path is too long: 01234
diff --git a/compiler-rt/test/sanitizer_common/TestCases/Posix/sanitizer_set_report_path_test.cpp b/compiler-rt/test/sanitizer_common/TestCases/Posix/sanitizer_set_report_path_test.cpp
--- a/compiler-rt/test/sanitizer_common/TestCases/Posix/sanitizer_set_report_path_test.cpp
+++ b/compiler-rt/test/sanitizer_common/TestCases/Posix/sanitizer_set_report_path_test.cpp
@@ -1,6 +1,11 @@
 // Test __sanitizer_set_report_path and __sanitizer_get_report_path:
+// RUN: rm -rf %t.report_path
 // RUN: %clangxx -O2 %s -o %t
 // RUN: %run %t | FileCheck %s
+// Try again with a directory without write access.
+// RUN: rm -rf %t.report_path && mkdir -p %t.report_path
+// RUN: chmod u-w %t.report_path || true
+// RUN: not %run %t 2>&1 | FileCheck %s --check-prefix=FAIL
 
 #include <assert.h>
 #include <sanitizer/common_interface_defs.h>
@@ -18,3 +23,4 @@
 }
 
 // CHECK: Path {{.*}}Posix/Output/sanitizer_set_report_path_test.cpp.tmp.report_path/report.
+// FAIL: ERROR: Can't open file: {{.*}}Posix/Output/sanitizer_set_report_path_test.cpp.tmp.report_path/report.