diff --git a/clang/lib/CodeGen/CGBlocks.cpp b/clang/lib/CodeGen/CGBlocks.cpp
index ea164aad915a..88786bc9fcf2 100644
--- a/clang/lib/CodeGen/CGBlocks.cpp
+++ b/clang/lib/CodeGen/CGBlocks.cpp
@@ -262,6 +262,11 @@ static bool isSafeForCXXConstantCapture(QualType type) {
 static llvm::Constant *tryCaptureAsConstant(CodeGenModule &CGM,
                                             CodeGenFunction *CGF,
                                             const VarDecl *var) {
+  // Don't rematerialize default arguments of function parameters.
+  if (auto *PD = dyn_cast<ParmVarDecl>(var))
+    if (PD->hasDefaultArg())
+      return nullptr;
+
   QualType type = var->getType();
 
   // We can only do this if the variable is const.
diff --git a/clang/test/CodeGenObjCXX/block-default-arg.mm b/clang/test/CodeGenObjCXX/block-default-arg.mm
new file mode 100644
index 000000000000..167b31d40549
--- /dev/null
+++ b/clang/test/CodeGenObjCXX/block-default-arg.mm
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10.0.0 -emit-llvm -o - %s -std=c++11 -fblocks -fobjc-arc | FileCheck  %s
+
+// CHECK: define internal void @___Z16test_default_argi_block_invoke(i8* %[[BLOCK_DESCRIPTOR:.*]])
+// CHECK: %[[BLOCK:.*]] = bitcast i8* %[[BLOCK_DESCRIPTOR]] to <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>*
+// CHECK: %[[BLOCK_CAPTURE_ADDR:.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>, <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, i32 }>* %[[BLOCK]], i32 0, i32 5
+// CHECK: %[[V0:.*]] = load i32, i32* %[[BLOCK_CAPTURE_ADDR]]
+// CHECK: call void @_Z4foo1i(i32 %[[V0]])
+
+void foo1(int);
+
+void test_default_arg(const int a = 42) {
+  auto block = ^{
+    foo1(a);
+  };
+  block();
+}