Index: lldb/trunk/source/Host/android/HostInfoAndroid.cpp
===================================================================
--- lldb/trunk/source/Host/android/HostInfoAndroid.cpp
+++ lldb/trunk/source/Host/android/HostInfoAndroid.cpp
@@ -91,11 +91,14 @@
 bool
 HostInfoAndroid::ComputeTempFileBaseDirectory(FileSpec &file_spec)
 {
-    if (HostInfoLinux::ComputeTempFileBaseDirectory(file_spec))
-        return true;
+    bool success = HostInfoLinux::ComputeTempFileBaseDirectory(file_spec);
 
-    // If the default mechanism for computing the temp directory failed then
-    // fall back to /data/local/tmp
-    file_spec = FileSpec("/data/local/tmp", false);
-    return true;
+    // On Android, there is no path which is guaranteed to be writable. If the user has not
+    // provided a path via an environment variable, the generic algorithm will deduce /tmp, which
+    // is plain wrong. In that case we have an invalid directory, we substitute the path with
+    // /data/local/tmp, which is correct at least in some cases (i.e., when running as shell user).
+    if (!success || !file_spec.Exists())
+        file_spec = FileSpec("/data/local/tmp", false);
+
+    return file_spec.Exists();
 }
Index: lldb/trunk/source/Host/common/HostInfoBase.cpp
===================================================================
--- lldb/trunk/source/Host/common/HostInfoBase.cpp
+++ lldb/trunk/source/Host/common/HostInfoBase.cpp
@@ -20,6 +20,7 @@
 #include "llvm/ADT/Triple.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/Host.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include <thread>
@@ -344,19 +345,9 @@
 bool
 HostInfoBase::ComputeTempFileBaseDirectory(FileSpec &file_spec)
 {
-    file_spec.Clear();
-
-    const char *tmpdir_cstr = getenv("TMPDIR");
-    if (tmpdir_cstr == nullptr)
-    {
-        tmpdir_cstr = getenv("TMP");
-        if (tmpdir_cstr == nullptr)
-            tmpdir_cstr = getenv("TEMP");
-    }
-    if (!tmpdir_cstr)
-        return false;
-
-    file_spec = FileSpec(tmpdir_cstr, false);
+    llvm::SmallVector<char, 16> tmpdir;
+    llvm::sys::path::system_temp_directory(/*ErasedOnReboot*/ true, tmpdir);
+    file_spec = FileSpec(std::string(tmpdir.data(), tmpdir.size()), true);
     return true;
 }