diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 7d634f5..d483149 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -2521,8 +2521,13 @@
     else if (A->getOption().matches(options::OPT_gdwarf_4))
       CmdArgs.push_back("-gdwarf-4");
     else if (!A->getOption().matches(options::OPT_g0) &&
-             !A->getOption().matches(options::OPT_ggdb0))
-      CmdArgs.push_back("-g");
+             !A->getOption().matches(options::OPT_ggdb0)) {
+      // Default is dwarf-2 for darwin.
+      if (getToolChain().getTriple().isOSDarwin())
+        CmdArgs.push_back("-gdwarf-2");
+      else
+        CmdArgs.push_back("-g");
+    }
   }
 
   // We ignore flags -gstrict-dwarf and -grecord-gcc-switches for now.
diff --git a/test/CodeGen/dwarf-version.c b/test/CodeGen/dwarf-version.c
index 739f18d..6624b67 100644
--- a/test/CodeGen/dwarf-version.c
+++ b/test/CodeGen/dwarf-version.c
@@ -1,6 +1,8 @@
 // RUN: %clang -target x86_64-linux-gnu -gdwarf-2 -S -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang -target x86_64-linux-gnu -gdwarf-3 -S -emit-llvm -o - %s | FileCheck %s --check-prefix=VER3
 // RUN: %clang -target x86_64-linux-gnu -gdwarf-4 -S -emit-llvm -o - %s | FileCheck %s --check-prefix=VER4
+// RUN: %clang -target x86_64-linux-gnu -g -S -emit-llvm -o - %s | FileCheck %s --check-prefix=LINUX
+// RUN: %clang -target x86_64-apple-darwin -g -S -emit-llvm -o - %s | FileCheck %s --check-prefix=DARWIN
 int main (void) {
   return 0;
 }
@@ -8,3 +10,5 @@
 // CHECK: metadata !{i32 2, metadata !"Dwarf Version", i32 2}
 // VER3: metadata !{i32 2, metadata !"Dwarf Version", i32 3}
 // VER4: metadata !{i32 2, metadata !"Dwarf Version", i32 4}
+// LINUX: metadata !{i32 2, metadata !"Dwarf Version", i32 3}
+// DARWIN: metadata !{i32 2, metadata !"Dwarf Version", i32 2}
diff --git a/test/Driver/clang-g-opts.c b/test/Driver/clang-g-opts.c
index f5d09fd..ee4eed7 100644
--- a/test/Driver/clang-g-opts.c
+++ b/test/Driver/clang-g-opts.c
@@ -5,5 +5,6 @@
 // RUN: %clang -### -S %s -g0 -g 2>&1 | FileCheck --check-prefix=CHECK-WITH-G    %s
 
 // CHECK-WITHOUT-G-NOT: "-g"
-// CHECK-WITH-G: "-g"
+// Can be -gdwarf.
+// CHECK-WITH-G: "-g
 
diff --git a/test/Driver/debug-options.c b/test/Driver/debug-options.c
index 981fa90..490b746 100644
--- a/test/Driver/debug-options.c
+++ b/test/Driver/debug-options.c
@@ -26,7 +26,8 @@
 // RUN:        | FileCheck -check-prefix=GIGNORE %s
 //
 // G: "-cc1"
-// G: "-g"
+// Can be -gdwarf.
+// G: "-g
 // 
 // G_D2: "-cc1"
 // G_D2: "-gdwarf-2"
@@ -41,7 +42,7 @@
 //
 // G_ONLY: "-cc1"
 // G_ONLY-NOT: "-gline-tables-only"
-// G_ONLY: "-g"
+// G_ONLY: "-g
 // G_ONLY-NOT: "-gline-tables-only"
 //
 // GLTO_NO: "-cc1"