diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -135,6 +135,9 @@
 
 Non-comprehensive list of changes in this release
 -------------------------------------------------
+- It's now possible to set the crash diagnostics directory through
+  the environment variable ``CLANG_CRASH_DIAGNOSTICS_DIR``.
+  The ``-fcrash-diagnostics-dir`` flag takes precedence.
 
 New Compiler Flags
 ------------------
diff --git a/clang/docs/UsersManual.rst b/clang/docs/UsersManual.rst
--- a/clang/docs/UsersManual.rst
+++ b/clang/docs/UsersManual.rst
@@ -687,6 +687,11 @@
   Specify where to write the crash diagnostics files; defaults to the
   usual location for temporary files.
 
+.. envvar:: CLANG_CRASH_DIAGNOSTICS_DIR=<dir>
+
+   Like :option:`-fcrash-diagnostics-dir=<dir>`, specifies where to write the
+   crash diagnostics files, but with lower precedence than the option.
+
 Clang is also capable of generating preprocessed source file(s) and associated
 run script(s) even without a crash. This is specially useful when trying to
 generate a reproducer for warnings or errors while using modules.
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -5413,15 +5413,18 @@
                                    StringRef BoundArch) const {
   SmallString<128> TmpName;
   Arg *A = C.getArgs().getLastArg(options::OPT_fcrash_diagnostics_dir);
-  if (CCGenDiagnostics && A) {
-    SmallString<128> CrashDirectory(A->getValue());
-    if (!getVFS().exists(CrashDirectory))
-      llvm::sys::fs::create_directories(CrashDirectory);
-    llvm::sys::path::append(CrashDirectory, Prefix);
+  Optional<std::string> CrashDirectory =
+      CCGenDiagnostics && A
+          ? std::string(A->getValue())
+          : llvm::sys::Process::GetEnv("CLANG_CRASH_DIAGNOSTICS_DIR");
+  if (CrashDirectory) {
+    if (!getVFS().exists(*CrashDirectory))
+      llvm::sys::fs::create_directories(*CrashDirectory);
+    SmallString<128> Path(*CrashDirectory);
+    llvm::sys::path::append(Path, Prefix);
     const char *Middle = !Suffix.empty() ? "-%%%%%%." : "-%%%%%%";
-    std::error_code EC = llvm::sys::fs::createUniqueFile(
-        CrashDirectory + Middle + Suffix, TmpName);
-    if (EC) {
+    if (std::error_code EC =
+            llvm::sys::fs::createUniqueFile(Path + Middle + Suffix, TmpName)) {
       Diag(clang::diag::err_unable_to_make_temp) << EC.message();
       return "";
     }
diff --git a/clang/test/Driver/crash-diagnostics-dir-3.c b/clang/test/Driver/crash-diagnostics-dir-3.c
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/crash-diagnostics-dir-3.c
@@ -0,0 +1,5 @@
+// RUN: rm -rf %t
+// RUN: not env CLANG_CRASH_DIAGNOSTICS_DIR=%t %clang -c %s -o - 2>&1 | FileCheck %s
+#pragma clang __debug parser_crash
+// CHECK: Preprocessed source(s) and associated run script(s) are located at:
+// CHECK: diagnostic msg: {{.*}}{{/|\\}}crash-diagnostics-dir-3.c.tmp{{(/|\\).*}}.c
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -369,10 +369,12 @@
     artifact_paths:
       - "**/test-results.xml"
       - "**/*.abilist"
+      - "**/crash_diagnostics/*"
     env:
         CC: "clang-${LLVM_HEAD_VERSION}"
         CXX: "clang++-${LLVM_HEAD_VERSION}"
         LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-${LLVM_HEAD_VERSION}"
+        CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
     agents:
       queue: "libcxx-builders"
       os: "linux"