diff --git a/include/llvm/CodeGen/PBQP/Graph.h b/include/llvm/CodeGen/PBQP/Graph.h
index 5240729f52d..a5d8b0dbd6a 100644
--- a/include/llvm/CodeGen/PBQP/Graph.h
+++ b/include/llvm/CodeGen/PBQP/Graph.h
@@ -350,6 +350,43 @@ namespace PBQP {
       numNodes = numEdges = 0;
     }
 
+    /// \brief Dump a graph to an output stream.
+    template <typename OStream>
+    void dump(OStream &os) {
+      os << getNumNodes() << " " << getNumEdges() << "\n";
+
+      for (NodeItr nodeItr = nodesBegin(), nodeEnd = nodesEnd();
+           nodeItr != nodeEnd; ++nodeItr) {
+        const Vector& v = getNodeCosts(nodeItr);
+        os << "\n" << v.getLength() << "\n";
+        assert(v.getLength() != 0 && "Empty vector in graph.");
+        os << v[0];
+        for (unsigned i = 1; i < v.getLength(); ++i) {
+          os << " " << v[i];
+        }
+        os << "\n";
+      }
+
+      for (EdgeItr edgeItr = edgesBegin(), edgeEnd = edgesEnd();
+           edgeItr != edgeEnd; ++edgeItr) {
+        unsigned n1 = std::distance(nodesBegin(), getEdgeNode1(edgeItr));
+        unsigned n2 = std::distance(nodesBegin(), getEdgeNode2(edgeItr));
+        assert(n1 != n2 && "PBQP graphs shound not have self-edges.");
+        const Matrix& m = getEdgeCosts(edgeItr);
+        os << "\n" << n1 << " " << n2 << "\n"
+           << m.getRows() << " " << m.getCols() << "\n";
+        assert(m.getRows() != 0 && "No rows in matrix.");
+        assert(m.getCols() != 0 && "No cols in matrix.");
+        for (unsigned i = 0; i < m.getRows(); ++i) {
+          os << m[i][0];
+          for (unsigned j = 1; j < m.getCols(); ++j) {
+            os << " " << m[i][j];
+          }
+          os << "\n";
+        }
+      }
+    }
+
     /// \brief Print a representation of this graph in DOT format.
     /// @param os Output stream to print on.
     template <typename OStream>
diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index 73f78e2a8d9..7d340baed31 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -36,6 +36,7 @@
 #include "Spiller.h"
 #include "VirtRegMap.h"
 #include "RegisterCoalescer.h"
+#include "llvm/Module.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/CodeGen/CalcSpillWeights.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
@@ -56,6 +57,7 @@
 #include <limits>
 #include <memory>
 #include <set>
+#include <sstream>
 #include <vector>
 
 using namespace llvm;
@@ -69,6 +71,13 @@ pbqpCoalescing("pbqp-coalescing",
                 cl::desc("Attempt coalescing during PBQP register allocation."),
                 cl::init(false), cl::Hidden);
 
+#ifndef NDEBUG
+static cl::opt<bool>
+pbqpDumpGraphs("pbqp-dump-graphs",
+               cl::desc("Dump graphs for each function/round in the compilation unit."),
+               cl::init(false), cl::Hidden);
+#endif
+
 namespace {
 
 ///
@@ -667,6 +676,12 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
   // Find the vreg intervals in need of allocation.
   findVRegIntervalsToAlloc();
 
+  const Function* func = mf->getFunction();
+  std::string fqn =
+    func->getParent()->getModuleIdentifier() + "." +
+    func->getName().str();
+  (void)fqn;
+
   // If there are non-empty intervals allocate them using pbqp.
   if (!vregsToAlloc.empty()) {
 
@@ -678,6 +693,20 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
 
       std::auto_ptr<PBQPRAProblem> problem =
         builder->build(mf, lis, loopInfo, vregsToAlloc);
+
+#ifndef NDEBUG
+      if (pbqpDumpGraphs) {
+        std::ostringstream rs;
+        rs << round;
+        std::string graphFileName(fqn + "." + rs.str() + ".pbqpgraph");
+        std::string tmp;
+        raw_fd_ostream os(graphFileName.c_str(), tmp);
+        DEBUG(dbgs() << "Dumping graph for round " << round << " to \""
+              << graphFileName << "\"\n");
+        problem->getGraph().dump(os);
+      }
+#endif
+
       PBQP::Solution solution =
         PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
           problem->getGraph());