Index: include/llvm/ADT/APFloat.h
===================================================================
--- include/llvm/ADT/APFloat.h
+++ include/llvm/ADT/APFloat.h
@@ -276,6 +276,10 @@
   /// \param isIEEE   - If 128 bit number, select between PPC and IEEE
   static APFloat getAllOnesValue(unsigned BitWidth, bool isIEEE = false);
 
+  /// Returns the size of the floating point number (in bits) in the given
+  /// semantics.
+  static unsigned getSizeInBits(const fltSemantics &Sem);
+
   /// @}
 
   /// Used to insert APFloat objects, or objects that contain APFloat objects,
Index: lib/Support/APFloat.cpp
===================================================================
--- lib/Support/APFloat.cpp
+++ lib/Support/APFloat.cpp
@@ -3368,6 +3368,21 @@
   }
 }
 
+unsigned APFloat::getSizeInBits(const fltSemantics &Sem)
+{
+  // sign bit + mantissa
+  unsigned size = 1 + Sem.precision;
+
+  // Add size of the exponent
+  ExponentType ex = Sem.maxExponent;
+  while (ex) {
+    ex >>= 1;
+    size++;
+  }
+
+  return size;
+}
+
 /// Make this number the largest magnitude normal number in the given
 /// semantics.
 void APFloat::makeLargest(bool Negative) {