diff --git a/lib/CodeGen/RegisterClassInfo.cpp b/lib/CodeGen/RegisterClassInfo.cpp
index 2d56ec3341b..9b106815ef0 100644
--- a/lib/CodeGen/RegisterClassInfo.cpp
+++ b/lib/CodeGen/RegisterClassInfo.cpp
@@ -39,7 +39,8 @@ void RegisterClassInfo::runOnMachineFunction(const MachineFunction &mf) {
   if (Update || CSR != CalleeSaved) {
     // Build a CSRNum map. Every CSR alias gets an entry pointing to the last
     // overlapping CSR.
-    CSRNum.reset(new uint8_t[TRI->getNumRegs()]());
+    CSRNum.clear();
+    CSRNum.resize(TRI->getNumRegs(), 0);
     for (unsigned N = 0; unsigned Reg = CSR[N]; ++N)
       for (const unsigned *AS = TRI->getOverlaps(Reg);
            unsigned Alias = *AS; ++AS)
diff --git a/lib/CodeGen/RegisterClassInfo.h b/lib/CodeGen/RegisterClassInfo.h
index 1ac040833ba..e41ae9e8dab 100644
--- a/lib/CodeGen/RegisterClassInfo.h
+++ b/lib/CodeGen/RegisterClassInfo.h
@@ -51,7 +51,7 @@ class RegisterClassInfo {
   const unsigned *CalleeSaved;
 
   // Map register number to CalleeSaved index + 1;
-  OwningArrayPtr<uint8_t> CSRNum;
+  SmallVector<uint8_t, 4> CSRNum;
 
   // Reserved registers in the current MF.
   BitVector Reserved;