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
@@ -277,7 +277,8 @@
   if (CCCIsCPP() || (PhaseArg = DAL.getLastArg(options::OPT_E)) ||
       (PhaseArg = DAL.getLastArg(options::OPT__SLASH_EP)) ||
       (PhaseArg = DAL.getLastArg(options::OPT_M, options::OPT_MM)) ||
-      (PhaseArg = DAL.getLastArg(options::OPT__SLASH_P))) {
+      (PhaseArg = DAL.getLastArg(options::OPT__SLASH_P)) ||
+      CCGenDiagnostics) {
     FinalPhase = phases::Preprocess;
 
   // --precompile only runs up to precompilation.
@@ -1343,7 +1344,6 @@
   PrintVersion(C, llvm::errs());
 
   // Suppress driver output and emit preprocessor output to temp file.
-  Mode = CPPMode;
   CCGenDiagnostics = true;
 
   // Save the original job command(s).
@@ -2263,6 +2263,7 @@
             //
             // Otherwise emit an error but still use a valid type to avoid
             // spurious errors (e.g., no inputs).
+            assert(!CCGenDiagnostics && "stdin produces no crash reproducer");
             if (!Args.hasArgNoClaim(options::OPT_E) && !CCCIsCPP())
               Diag(IsCLMode() ? clang::diag::err_drv_unknown_stdin_type_clang_cl
                               : clang::diag::err_drv_unknown_stdin_type);
@@ -2278,10 +2279,10 @@
             Ty = TC.LookupTypeForExtension(Ext + 1);
 
           if (Ty == types::TY_INVALID) {
-            if (CCCIsCPP())
-              Ty = types::TY_C;
-            else if (IsCLMode() && Args.hasArgNoClaim(options::OPT_E))
+            if (IsCLMode() && (Args.hasArgNoClaim(options::OPT_E) || CCGenDiagnostics))
               Ty = types::TY_CXX;
+            else if (CCCIsCPP() || CCGenDiagnostics)
+              Ty = types::TY_C;
             else
               Ty = types::TY_Object;
           }
diff --git a/clang/test/Driver/crash-report-clang-cl.c b/clang/test/Driver/crash-report-clang-cl.c
deleted file mode 100644
--- a/clang/test/Driver/crash-report-clang-cl.c
+++ /dev/null
@@ -1,24 +0,0 @@
-// RUN: rm -rf %t
-// RUN: mkdir %t
-
-// RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1           \
-// RUN: not %clang_cl -fsyntax-only /Brepro /source-charset:utf-8 \
-// RUN:     -- %s 2>&1 | FileCheck %s
-// RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
-
-// REQUIRES: crash-recovery
-
-#pragma clang __debug crash
-
-// CHECK: Preprocessed source(s) and associated run script(s) are located at:
-// CHECK-NEXT: note: diagnostic msg: {{.*}}crash-report-clang-cl-{{.*}}.c
-// CHECKSH: # Crash reproducer
-// CHECKSH-NEXT: # Driver args: {{.*}}"-fsyntax-only"
-// CHECKSH-SAME: /Brepro
-// CHECKSH-SAME: /source-charset:utf-8
-// CHECKSH-NOT: -mno-incremental-linker-compatible
-// CHECKSH-NOT: -finput-charset=utf-8
-// CHECKSH-NEXT: # Original command: {{.*$}}
-// CHECKSH-NEXT: "-cc1"
-// CHECKSH: "-main-file-name" "crash-report-clang-cl.c"
-// CHECKSH: "crash-report-{{[^ ]*}}.c"
diff --git a/clang/test/Driver/crash-report-clang-cl.cpp b/clang/test/Driver/crash-report-clang-cl.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/crash-report-clang-cl.cpp
@@ -0,0 +1,45 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+
+// RUN: not %clang_cl -fsyntax-only /Brepro /source-charset:utf-8 \
+// RUN:     -fcrash-diagnostics-dir=%t -- %s 2>&1 | FileCheck %s
+// RUN: cat %t/crash-report-clang-cl-*.cpp | FileCheck --check-prefix=CHECKSRC %s
+// RUN: cat %t/crash-report-clang-cl-*.sh | FileCheck --check-prefix=CHECKSH %s
+
+// REQUIRES: crash-recovery
+
+#pragma clang __debug crash
+
+// CHECK: Preprocessed source(s) and associated run script(s) are located at:
+
+// __has_feature(cxx_exceptions) is default-off in the cl-compatible driver.
+FOO
+#if __has_feature(cxx_exceptions)
+int a = 1;
+#else
+int a = 0;
+#endif
+// CHECKSRC:      {{^}}FOO
+// CHECKSRC-NEXT: {{^}}#if 0 /* disabled by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#if __has_feature(cxx_exceptions)
+// CHECKSRC-NEXT: {{^}}#endif
+// CHECKSRC-NEXT: {{^}}#endif /* disabled by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#if 0 /* evaluated by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#
+// CHECKSRC-NEXT: {{^}}int a = 1;
+// CHECKSRC-NEXT: {{^}}#else
+// CHECKSRC-NEXT: {{^}}#
+// CHECKSRC-NEXT: {{^}}int a = 0;
+// CHECKSRC-NEXT: {{^}}#endif
+
+// CHECK-NEXT: note: diagnostic msg: {{.*}}crash-report-clang-cl-{{.*}}.cpp
+// CHECKSH: # Crash reproducer
+// CHECKSH-NEXT: # Driver args: {{.*}}"-fsyntax-only"
+// CHECKSH-SAME: /Brepro
+// CHECKSH-SAME: /source-charset:utf-8
+// CHECKSH-NOT: -mno-incremental-linker-compatible
+// CHECKSH-NOT: -finput-charset=utf-8
+// CHECKSH-NEXT: # Original command: {{.*$}}
+// CHECKSH-NEXT: "-cc1"
+// CHECKSH: "-main-file-name" "crash-report-clang-cl.cpp"
+// CHECKSH: "crash-report-{{[^ ]*}}.cpp"
diff --git a/clang/test/Driver/crash-report.c b/clang/test/Driver/crash-report.cpp
rename from clang/test/Driver/crash-report.c
rename to clang/test/Driver/crash-report.cpp
--- a/clang/test/Driver/crash-report.c
+++ b/clang/test/Driver/crash-report.cpp
@@ -6,25 +6,25 @@
 // RUN:  -iprefix /the/prefix -iwithprefix /tmp -iwithprefixbefore /tmp/ \
 // RUN:  -Xclang -internal-isystem -Xclang /tmp/                         \
 // RUN:  -Xclang -internal-externc-isystem -Xclang /tmp/                 \
-// RUN:  -Xclang -main-file-name -Xclang foo.c                           \
+// RUN:  -Xclang -main-file-name -Xclang foo.cpp                         \
 // RUN:  -DFOO=BAR -DBAR="BAZ QUX"' > %t.rsp
 
 // RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1                  \
 // RUN:  CC_PRINT_HEADERS=1 CC_LOG_DIAGNOSTICS=1                         \
 // RUN:  not %clang %s @%t.rsp -DPARSER 2>&1 | FileCheck %s
-// RUN: cat %t/crash-report-*.c | FileCheck --check-prefix=CHECKSRC %s
+// RUN: cat %t/crash-report-*.cpp | FileCheck --check-prefix=CHECKSRC %s
 // RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
 
 // RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1                  \
 // RUN:  CC_PRINT_HEADERS=1 CC_LOG_DIAGNOSTICS=1                         \
 // RUN:  not %clang %s @%t.rsp -DCRASH 2>&1 | FileCheck %s
-// RUN: cat %t/crash-report-*.c | FileCheck --check-prefix=CHECKSRC %s
+// RUN: cat %t/crash-report-*.cpp | FileCheck --check-prefix=CHECKSRC %s
 // RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
 
 // RUN: env TMPDIR=%t TEMP=%t TMP=%t RC_DEBUG_OPTIONS=1                  \
 // RUN:  CC_PRINT_HEADERS=1 CC_LOG_DIAGNOSTICS=1                         \
 // RUN:  not %clang %s @%t.rsp -DFATAL 2>&1 | FileCheck %s
-// RUN: cat %t/crash-report-*.c | FileCheck --check-prefix=CHECKSRC %s
+// RUN: cat %t/crash-report-*.cpp | FileCheck --check-prefix=CHECKSRC %s
 // RUN: cat %t/crash-report-*.sh | FileCheck --check-prefix=CHECKSH %s
 
 // REQUIRES: crash-recovery
@@ -38,16 +38,35 @@
 #endif
 
 // CHECK: Preprocessed source(s) and associated run script(s) are located at:
-// CHECK-NEXT: note: diagnostic msg: {{.*}}crash-report-{{.*}}.c
+// CHECK-NEXT: note: diagnostic msg: {{.*}}crash-report-{{.*}}.cpp
+
+// __has_feature(cxx_exceptions) is default-on in the gcc-compatible driver.
 FOO
-// CHECKSRC: FOO
+#if __has_feature(cxx_exceptions)
+int a = 1;
+#else
+int a = 0;
+#endif
+// CHECKSRC:      {{^}}FOO
+// CHECKSRC-NEXT: {{^}}#if 0 /* disabled by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#if __has_feature(cxx_exceptions)
+// CHECKSRC-NEXT: {{^}}#endif
+// CHECKSRC-NEXT: {{^}}#endif /* disabled by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#if 1 /* evaluated by -frewrite-includes */
+// CHECKSRC-NEXT: {{^}}#
+// CHECKSRC-NEXT: {{^}}int a = 1;
+// CHECKSRC-NEXT: {{^}}#else
+// CHECKSRC-NEXT: {{^}}#
+// CHECKSRC-NEXT: {{^}}int a = 0;
+// CHECKSRC-NEXT: {{^}}#endif
+
 // CHECKSH: # Crash reproducer
 // CHECKSH-NEXT: # Driver args: {{.*}}"-fsyntax-only"
 // CHECKSH-SAME: "-D" "FOO=BAR"
 // CHECKSH-SAME: "-D" "BAR=BAZ QUX"
 // CHECKSH-NEXT: # Original command: {{.*$}}
 // CHECKSH-NEXT: "-cc1"
-// CHECKSH: "-main-file-name" "crash-report.c"
+// CHECKSH: "-main-file-name" "crash-report.cpp"
 // CHECKSH-NOT: "-header-include-file"
 // CHECKSH-NOT: "-diagnostic-log-file"
 // CHECKSH: "-D" "FOO=BAR"
@@ -63,4 +82,4 @@
 // CHECKSH-NOT: "-internal-isystem" "/tmp/"
 // CHECKSH-NOT: "-internal-externc-isystem" "/tmp/"
 // CHECKSH-NOT: "-dwarf-debug-flags"
-// CHECKSH: "crash-report-{{[^ ]*}}.c"
+// CHECKSH: "crash-report-{{[^ ]*}}.cpp"