Index: llvm/trunk/include/llvm/CodeGen/MIRYamlMapping.h
===================================================================
--- llvm/trunk/include/llvm/CodeGen/MIRYamlMapping.h
+++ llvm/trunk/include/llvm/CodeGen/MIRYamlMapping.h
@@ -20,6 +20,34 @@
 
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/YAMLTraits.h"
+#include <vector>
+
+namespace llvm {
+namespace yaml {
+
+struct MachineBasicBlock {
+  std::string Name;
+  unsigned Alignment = 0;
+  bool IsLandingPad = false;
+  bool AddressTaken = false;
+  // TODO: Serialize the successors and liveins.
+  // TODO: Serialize machine instructions.
+};
+
+template <> struct MappingTraits<MachineBasicBlock> {
+  static void mapping(IO &YamlIO, MachineBasicBlock &MBB) {
+    YamlIO.mapOptional("name", MBB.Name,
+                       std::string()); // Don't print out an empty name.
+    YamlIO.mapOptional("alignment", MBB.Alignment);
+    YamlIO.mapOptional("isLandingPad", MBB.IsLandingPad);
+    YamlIO.mapOptional("addressTaken", MBB.AddressTaken);
+  }
+};
+
+} // end namespace yaml
+} // end namespace llvm
+
+LLVM_YAML_IS_SEQUENCE_VECTOR(llvm::yaml::MachineBasicBlock)
 
 namespace llvm {
 namespace yaml {
@@ -29,6 +57,8 @@
   unsigned Alignment = 0;
   bool ExposesReturnsTwice = false;
   bool HasInlineAsm = false;
+
+  std::vector<MachineBasicBlock> BasicBlocks;
 };
 
 template <> struct MappingTraits<MachineFunction> {
@@ -37,6 +67,7 @@
     YamlIO.mapOptional("alignment", MF.Alignment);
     YamlIO.mapOptional("exposesReturnsTwice", MF.ExposesReturnsTwice);
     YamlIO.mapOptional("hasInlineAsm", MF.HasInlineAsm);
+    YamlIO.mapOptional("body", MF.BasicBlocks);
   }
 };
 
Index: llvm/trunk/lib/CodeGen/MIRParser/MIRParser.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MIRParser/MIRParser.cpp
+++ llvm/trunk/lib/CodeGen/MIRParser/MIRParser.cpp
@@ -19,10 +19,12 @@
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MIRYamlMapping.h"
+#include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
+#include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/SMLoc.h"
 #include "llvm/Support/SourceMgr.h"
@@ -74,6 +76,12 @@
   /// Return true if error occurred.
   bool initializeMachineFunction(MachineFunction &MF);
 
+  /// Initialize the machine basic block using it's YAML representation.
+  ///
+  /// Return true if an error occurred.
+  bool initializeMachineBasicBlock(MachineBasicBlock &MBB,
+                                   const yaml::MachineBasicBlock &YamlMBB);
+
 private:
   /// Return a MIR diagnostic converted from an LLVM assembly diagnostic.
   SMDiagnostic diagFromLLVMAssemblyDiag(const SMDiagnostic &Error,
@@ -198,6 +206,28 @@
     MF.setAlignment(YamlMF.Alignment);
   MF.setExposesReturnsTwice(YamlMF.ExposesReturnsTwice);
   MF.setHasInlineAsm(YamlMF.HasInlineAsm);
+  const auto &F = *MF.getFunction();
+  for (const auto &YamlMBB : YamlMF.BasicBlocks) {
+    const BasicBlock *BB = nullptr;
+    if (!YamlMBB.Name.empty()) {
+      BB = dyn_cast_or_null<BasicBlock>(
+          F.getValueSymbolTable().lookup(YamlMBB.Name));
+      // TODO: Report an error if a basic block isn't found.
+    }
+    auto *MBB = MF.CreateMachineBasicBlock(BB);
+    MF.insert(MF.end(), MBB);
+    if (initializeMachineBasicBlock(*MBB, YamlMBB))
+      return true;
+  }
+  return false;
+}
+
+bool MIRParserImpl::initializeMachineBasicBlock(
+    MachineBasicBlock &MBB, const yaml::MachineBasicBlock &YamlMBB) {
+  MBB.setAlignment(YamlMBB.Alignment);
+  if (YamlMBB.AddressTaken)
+    MBB.setHasAddressTaken();
+  MBB.setIsLandingPad(YamlMBB.IsLandingPad);
   return false;
 }
 
Index: llvm/trunk/lib/CodeGen/MIRPrinter.cpp
===================================================================
--- llvm/trunk/lib/CodeGen/MIRPrinter.cpp
+++ llvm/trunk/lib/CodeGen/MIRPrinter.cpp
@@ -16,6 +16,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MIRYamlMapping.h"
+#include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
@@ -34,6 +35,8 @@
   MIRPrinter(raw_ostream &OS) : OS(OS) {}
 
   void print(const MachineFunction &MF);
+
+  void convert(yaml::MachineBasicBlock &YamlMBB, const MachineBasicBlock &MBB);
 };
 
 } // end anonymous namespace
@@ -61,10 +64,27 @@
   YamlMF.Alignment = MF.getAlignment();
   YamlMF.ExposesReturnsTwice = MF.exposesReturnsTwice();
   YamlMF.HasInlineAsm = MF.hasInlineAsm();
+  for (const auto &MBB : MF) {
+    yaml::MachineBasicBlock YamlMBB;
+    convert(YamlMBB, MBB);
+    YamlMF.BasicBlocks.push_back(YamlMBB);
+  }
   yaml::Output Out(OS);
   Out << YamlMF;
 }
 
+void MIRPrinter::convert(yaml::MachineBasicBlock &YamlMBB,
+                         const MachineBasicBlock &MBB) {
+  // TODO: Serialize unnamed BB references.
+  if (const auto *BB = MBB.getBasicBlock())
+    YamlMBB.Name = BB->hasName() ? BB->getName() : "<unnamed bb>";
+  else
+    YamlMBB.Name = "";
+  YamlMBB.Alignment = MBB.getAlignment();
+  YamlMBB.AddressTaken = MBB.hasAddressTaken();
+  YamlMBB.IsLandingPad = MBB.isLandingPad();
+}
+
 void llvm::printMIR(raw_ostream &OS, const Module &M) {
   yaml::Output Out(OS);
   Out << const_cast<Module &>(M);
Index: llvm/trunk/test/CodeGen/MIR/basic-blocks.mir
===================================================================
--- llvm/trunk/test/CodeGen/MIR/basic-blocks.mir
+++ llvm/trunk/test/CodeGen/MIR/basic-blocks.mir
@@ -0,0 +1,43 @@
+# RUN: llc -start-after branch-folder -stop-after branch-folder -o /dev/null %s | FileCheck %s
+# This test ensures that the MIR parser parses machine functions correctly.
+
+--- |
+
+  define i32 @foo() {
+  entry:
+    ret i32 0
+  }
+
+  define i32 @bar() {
+  start:
+    ret i32 0
+  }
+
+...
+---
+# CHECK: name: foo
+# CHECK: body:
+# CHECK-NEXT: - name: entry
+# CHECK-NEXT:   alignment: 0
+# CHECK-NEXT:   isLandingPad: false
+# CHECK-NEXT:   addressTaken: false
+name:            foo
+body:
+ - name:         entry
+...
+---
+# CHECK: name: bar
+# CHECK: body:
+# CHECK-NEXT: - name: start
+# CHECK-NEXT:   alignment: 4
+# CHECK-NEXT:   isLandingPad: false
+# CHECK-NEXT:   addressTaken: false
+# CHECK-NEXT: - alignment: 0
+# CHECK-NEXT:   isLandingPad: false
+# CHECK-NEXT:   addressTaken: true
+name:            bar
+body:
+ - name:         start
+   alignment:    4
+ - addressTaken: true
+...