diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index c521bf9..77e29bd 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -1157,10 +1157,24 @@
     // There might not be a capture for 'self', but if there is...
     if (blockInfo.Captures.count(self)) {
       const CGBlockInfo::Capture &capture = blockInfo.getCapture(self);
+
       llvm::Value *selfAddr = Builder.CreateStructGEP(BlockPointer,
                                                       capture.getIndex(),
                                                       "block.captured-self");
-      LocalDeclMap[self] = selfAddr;
+
+      // At -O0 we generate an explicit alloca for self to facilitate debugging.
+      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
+	llvm::Value *load = Builder.CreateLoad(selfAddr);
+
+	// Allocate a stack slot for it, so we can generate debug info for it
+	llvm::AllocaInst *alloca = CreateTempAlloca(load->getType(),
+                                                   "block.captured-self.addr");
+        unsigned align = getContext().getDeclAlign(self).getQuantity();
+        alloca->setAlignment(align);
+	Builder.CreateAlignedStore(load, alloca, align);
+        LocalDeclMap[self] = alloca;
+      } else
+        LocalDeclMap[self] = selfAddr;
     }
   }
 
@@ -1177,7 +1191,7 @@
       CreateMemTemp(variable->getType(), "block.captured-const");
     alloca->setAlignment(align);
 
-    Builder.CreateStore(capture.getConstant(), alloca, align);
+    Builder.CreateAlignedStore(capture.getConstant(), alloca, align);
 
     LocalDeclMap[variable] = alloca;
   }
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 4aed943..6b0edbc 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -2680,7 +2680,8 @@
 }
 
 void CGDebugInfo::EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
-                                                       llvm::Value *addr,
+                                                       llvm::Value *Arg,
+                                                       llvm::Value *LocalAddr,
                                                        CGBuilderTy &Builder) {
   assert(CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo);
   ASTContext &C = CGM.getContext();
@@ -2807,21 +2808,26 @@
   // Get overall information about the block.
   unsigned flags = llvm::DIDescriptor::FlagArtificial;
   llvm::MDNode *scope = LexicalBlockStack.back();
-  StringRef name = ".block_descriptor";
 
   // Create the descriptor for the parameter.
   llvm::DIVariable debugVar =
     DBuilder.createLocalVariable(llvm::dwarf::DW_TAG_arg_variable,
                                  llvm::DIDescriptor(scope), 
-                                 name, tunit, line, type, 
+                                 Arg->getName(), tunit, line, type,
                                  CGM.getLangOpts().Optimize, flags,
-                                 cast<llvm::Argument>(addr)->getArgNo() + 1);
-    
-  // Insert an llvm.dbg.value into the current block.
-  llvm::Instruction *declare =
-    DBuilder.insertDbgValueIntrinsic(addr, 0, debugVar,
-                                     Builder.GetInsertBlock());
-  declare->setDebugLoc(llvm::DebugLoc::get(line, column, scope));
+                                 cast<llvm::Argument>(Arg)->getArgNo() + 1);
+
+  // Matching the code in EmitParmDecl, depending on optimization level.
+  llvm::Instruction *Call;
+  if (LocalAddr)
+    // Insert an llvm.dbg.value into the current block.
+    Call = DBuilder.insertDbgValueIntrinsic(LocalAddr, 0, debugVar,
+                                            Builder.GetInsertBlock());
+  else
+    // Insert an llvm.dbg.declare into the current block.
+    Call = DBuilder.insertDeclare(Arg, debugVar, Builder.GetInsertBlock());
+
+  Call->setDebugLoc(llvm::DebugLoc::get(line, column, scope));
 }
 
 /// getStaticDataMemberDeclaration - If D is an out-of-class definition of
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 73dd153..0d9c92e 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -248,7 +248,8 @@
   /// llvm.dbg.declare for the block-literal argument to a block
   /// invocation function.
   void EmitDeclareOfBlockLiteralArgVariable(const CGBlockInfo &block,
-                                            llvm::Value *addr,
+                                            llvm::Value *Arg,
+                                            llvm::Value *LocalAddr,
                                             CGBuilderTy &Builder);
 
   /// EmitGlobalVariable - Emit information about a global variable.
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index f9f48ae..3b33c11 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -1513,17 +1513,29 @@
 
   Arg->setName(D.getName());
 
+  QualType Ty = D.getType();
+
   // Use better IR generation for certain implicit parameters.
   if (isa<ImplicitParamDecl>(D)) {
     // The only implicit argument a block has is its literal.
     if (BlockInfo) {
       LocalDeclMap[&D] = Arg;
+      llvm::Value *LocalAddr = 0;
+      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
+        // Allocate a stack slot to let debug info survive the RA.
+        llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
+                                                   D.getName() + ".addr");
+        Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
+        LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D));
+        EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
+        LocalAddr = Builder.CreateLoad(Alloc);
+      }
 
       if (CGDebugInfo *DI = getDebugInfo()) {
         if (CGM.getCodeGenOpts().getDebugInfo()
               >= CodeGenOptions::LimitedDebugInfo) {
           DI->setLocation(D.getLocation());
-          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder);
+          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder);
         }
       }
 
@@ -1531,8 +1543,6 @@
     }
   }
 
-  QualType Ty = D.getType();
-
   llvm::Value *DeclPtr;
   // If this is an aggregate or variable sized value, reuse the input pointer.
   if (!Ty->isConstantSizeType() ||
diff --git a/test/CodeGenCXX/blocks.cpp b/test/CodeGenCXX/blocks.cpp
index 1500c0d..2092139 100644
--- a/test/CodeGenCXX/blocks.cpp
+++ b/test/CodeGenCXX/blocks.cpp
@@ -120,8 +120,10 @@
   }
   // CHECK: define void @_ZN5test44testEv()
   // CHECK: define internal void @___ZN5test44testEv_block_invoke
-  // CHECK:      [[TMP:%.*]] = alloca [[A:%.*]], align 1
-  // CHECK-NEXT: bitcast i8*
+  // CHECK: [[TMP:%.*]] = alloca [[A:%.*]], align 1
+  // CHECK-NEXT: store i8* [[BLOCKDESC:%.*]], i8** {{.*}}, align 8
+  // CHECK-NEXT: load i8*
+  // CHECK-NEXT: bitcast i8* [[BLOCKDESC]] to <{ i8*, i32, i32, i8*, %struct.__block_descriptor* }>*
   // CHECK-NEXT: call void @_ZN5test41AC1Ev([[A]]* [[TMP]])
   // CHECK-NEXT: call void @_ZN5test43fooENS_1AE([[A]]* [[TMP]])
   // CHECK-NEXT: call void @_ZN5test41AD1Ev([[A]]* [[TMP]])
diff --git a/test/CodeGenObjC/debug-info-block-captured-self.m b/test/CodeGenObjC/debug-info-block-captured-self.m
new file mode 100644
index 0000000..6020e84
--- /dev/null
+++ b/test/CodeGenObjC/debug-info-block-captured-self.m
@@ -0,0 +1,64 @@
+// RUN: %clang_cc1 -fblocks -g -emit-llvm -triple x86_64-apple-darwin -o - %s | FileCheck %s
+//
+// Test that debug location is generated for a captured "self" inside
+// a block.
+//
+// This test is split into two parts, this one for the frontend, and
+// then llvm/test/DebugInfo/debug-info-block-captured-self.ll to
+// ensure that DW_AT_location is generated for the captured self.
+@class T;
+@interface S
+@end
+@interface Mode
+-(int) count;
+@end
+@interface Context
+@end
+@interface ViewController
+@property (nonatomic, readwrite, strong) Context *context;
+@end
+typedef enum {
+    Unknown = 0,
+} State;
+@interface Main : ViewController
+{
+    T * t1;
+    T * t2;
+}
+@property(readwrite, nonatomic) State state;
+@end
+@implementation Main
+- (id) initWithContext:(Context *) context
+{
+    t1 = [self.context withBlock:^(id obj){
+        id *mode1;
+	t2 = [mode1 withBlock:^(id object){
+	    Mode *mode2 = object;
+	    if ([mode2 count] != 0) {
+	      self.state = 0;
+	    }
+	  }];
+      }];
+}
+@end
+// The important part of this test is that there is a dbg.value
+// intrinsic associated with the implicit .block_descriptor argument
+// of the block. We also test that this value gets alloca'd, so the
+// register llocator won't accidentally kill it.
+
+// outer block:
+// CHECK: define internal void {{.*}}_block_invoke{{.*}}
+
+// inner block:
+// CHECK: define internal void {{.*}}_block_invoke{{.*}}
+// CHECK:        [[MEM1:%.*]] = alloca i8*, align 8
+// CHECK-NEXT:   [[MEM2:%.*]] = alloca i8*, align 8
+// CHECK-NEXT:   [[MEM3:%.*]] = alloca %{{.*}}*, align 8
+// CHECK:        store i8* %[[BLOCK_DESC:.*]], i8** [[MEM1]], align 8
+// CHECK:        [[TMP0:%.*]] = load i8** [[MEM1]]
+// CHECK:        call void @llvm.dbg.value(metadata !{i8* [[TMP0]]}, i64 0, metadata [[BDMD:![0-9]+]])
+// CHECK:        [[TMP1:%.*]] = bitcast
+// CHECK-NEXT:   [[TMP2:%.*]] = getelementptr inbounds <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>* [[TMP1]]
+// CHECK-NEXT:   [[TMP3:%.*]] = load %0** [[TMP2]]
+// CHECK-NEXT:   store {{.*}}* [[TMP3]], %{{.*}}** [[MEM3]], align 8
+// CHECK:        [[BDMD]] = metadata {{.*}}.block_descriptor