diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -743,6 +743,10 @@
   /// True if this function needs frame moves for debug or exceptions.
   bool needsFrameMoves() const;
 
+  /// Estimate the total size of instructions, constants and jump table entries
+  /// in bytes. This may overestimate the function size.
+  unsigned estimateSizeInBytes() const;
+
   /// Get the function properties
   const MachineFunctionProperties &getProperties() const { return Properties; }
   MachineFunctionProperties &getProperties() { return Properties; }
diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -614,6 +614,25 @@
          F.needsUnwindTableEntry();
 }
 
+/// Estimate the total size of instructions, constants and jump table entries
+/// in bytes. This may overestimate the function size.
+unsigned MachineFunction::estimateSizeInBytes() const {
+  unsigned FnSize = 0;
+  const TargetInstrInfo *TII = getSubtarget().getInstrInfo();
+  const DataLayout &DL = getDataLayout();
+  for (auto &MBB : *this)
+    for (auto &MI : MBB)
+      FnSize += TII->getInstSizeInBytes(MI);
+  for (auto &C : getConstantPool()->getConstants())
+    FnSize += std::max(C.getSizeInBytes(DL), (unsigned)C.getAlign().value());
+  const MachineJumpTableInfo *JTI = getJumpTableInfo();
+  if (JTI)
+    for (auto &Table : JTI->getJumpTables())
+      FnSize += Table.MBBs.size() *
+                std::max(JTI->getEntrySize(DL), JTI->getEntryAlignment(DL));
+  return FnSize;
+}
+
 namespace llvm {
 
   template<>
diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
--- a/llvm/lib/Target/ARM/ARMFrameLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -2042,21 +2042,6 @@
   return true;
 }
 
-// FIXME: Make generic?
-static unsigned EstimateFunctionSizeInBytes(const MachineFunction &MF,
-                                            const ARMBaseInstrInfo &TII) {
-  unsigned FnSize = 0;
-  for (auto &MBB : MF) {
-    for (auto &MI : MBB)
-      FnSize += TII.getInstSizeInBytes(MI);
-  }
-  if (MF.getJumpTableInfo())
-    for (auto &Table: MF.getJumpTableInfo()->getJumpTables())
-      FnSize += Table.MBBs.size() * 4;
-  FnSize += MF.getConstantPool()->getConstants().size() * 4;
-  return FnSize;
-}
-
 /// estimateRSStackSizeLimit - Look at each instruction that references stack
 /// frames and return the stack size limit beyond which some of these
 /// instructions will require a scratch register during their expansion later.
@@ -2251,8 +2236,6 @@
   SmallVector<unsigned, 4> UnspilledCS2GPRs;
   const ARMBaseRegisterInfo *RegInfo = static_cast<const ARMBaseRegisterInfo *>(
       MF.getSubtarget().getRegisterInfo());
-  const ARMBaseInstrInfo &TII =
-      *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
   ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   MachineFrameInfo &MFI = MF.getFrameInfo();
   MachineRegisterInfo &MRI = MF.getRegInfo();
@@ -2377,7 +2360,7 @@
 
   bool ForceLRSpill = false;
   if (!LRSpilled && AFI->isThumb1OnlyFunction()) {
-    unsigned FnSize = EstimateFunctionSizeInBytes(MF, TII);
+    unsigned FnSize = MF.estimateSizeInBytes();
     // Force LR to be spilled if the Thumb function size is > 2048. This enables
     // use of BL to implement far jump.
     if (FnSize >= (1 << 11)) {
diff --git a/llvm/lib/Target/CSKY/CSKYFrameLowering.cpp b/llvm/lib/Target/CSKY/CSKYFrameLowering.cpp
--- a/llvm/lib/Target/CSKY/CSKYFrameLowering.cpp
+++ b/llvm/lib/Target/CSKY/CSKYFrameLowering.cpp
@@ -271,17 +271,6 @@
             MachineInstr::FrameDestroy);
 }
 
-static unsigned EstimateFunctionSizeInBytes(const MachineFunction &MF,
-                                            const CSKYInstrInfo &TII) {
-  unsigned FnSize = 0;
-  for (auto &MBB : MF) {
-    for (auto &MI : MBB)
-      FnSize += TII.getInstSizeInBytes(MI);
-  }
-  FnSize += MF.getConstantPool()->getConstants().size() * 4;
-  return FnSize;
-}
-
 static unsigned estimateRSStackSizeLimit(MachineFunction &MF,
                                          const CSKYSubtarget &STI) {
   unsigned Limit = (1 << 12) - 1;
@@ -361,7 +350,6 @@
 
   CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
-  const CSKYInstrInfo *TII = STI.getInstrInfo();
   const MachineRegisterInfo &MRI = MF.getRegInfo();
   MachineFrameInfo &MFI = MF.getFrameInfo();
 
@@ -444,7 +432,7 @@
     RS->addScavengingFrameIndex(MFI.CreateStackObject(size, align, false));
   }
 
-  unsigned FnSize = EstimateFunctionSizeInBytes(MF, *TII);
+  unsigned FnSize = MF.estimateSizeInBytes();
   // Force R15 to be spilled if the function size is > 65534. This enables
   // use of BSR to implement far jump.
   if (FnSize >= ((1 << (16 - 1)) * 2))