diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -2289,6 +2289,25 @@
 
   unsigned VWidth = cast<FixedVectorType>(SVI.getType())->getNumElements();
   unsigned LHSWidth = cast<FixedVectorType>(LHS->getType())->getNumElements();
+
+  // shuffle (bitcast X), (bitcast Y), Mask --> bitcast (shuffle X, Y, Mask)
+  //
+  // if X and Y are of the same (vector) type, and the element size is not
+  // changed by the bitcasts, we can distribute the bitcasts through the
+  // shuffle, hopefully reducing the number of instructions. We make sure that
+  // at least one bitcast only has one use, so we don't *increase* the number of
+  // instructions here.
+  Value *X, *Y;
+  if (match(LHS, m_BitCast(m_Value(X))) && match(RHS, m_BitCast(m_Value(Y))) &&
+      X->getType()->isVectorTy() && X->getType() == Y->getType() &&
+      X->getType()->getScalarSizeInBits() ==
+          SVI.getType()->getScalarSizeInBits() &&
+      (LHS->hasOneUse() || RHS->hasOneUse())) {
+    Value *V = Builder.CreateShuffleVector(X, Y, SVI.getShuffleMask(),
+                                           SVI.getName() + ".uncasted");
+    return new BitCastInst(V, SVI.getType());
+  }
+
   ArrayRef<int> Mask = SVI.getShuffleMask();
   Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
 
@@ -2298,7 +2317,6 @@
   // TODO: This could be extended to allow length-changing shuffles.
   //       The transform might also be obsoleted if we allowed canonicalization
   //       of bitcasted shuffles.
-  Value *X;
   if (match(LHS, m_BitCast(m_Value(X))) && match(RHS, m_Undef()) &&
       X->getType()->isVectorTy() && VWidth == LHSWidth) {
     // Try to create a scaled mask constant.
diff --git a/llvm/test/Transforms/InstCombine/shuffle-cast-dist.ll b/llvm/test/Transforms/InstCombine/shuffle-cast-dist.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/shuffle-cast-dist.ll
@@ -0,0 +1,153 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define <2 x float> @vtrn1(<2 x i32> %v)
+; CHECK-LABEL: @vtrn1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[R_UNCASTED:%.*]] = shufflevector <2 x i32> [[V:%.*]], <2 x i32> undef, <2 x i32> zeroinitializer
+; CHECK-NEXT:    [[R:%.*]] = bitcast <2 x i32> [[R_UNCASTED]] to <2 x float>
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+{
+entry:
+  %vb1 = bitcast <2 x i32> %v to <2 x float>
+  %vb2 = bitcast <2 x i32> %v to <2 x float>
+  %r = shufflevector <2 x float> %vb1, <2 x float> %vb2, <2 x i32> <i32 0, i32 2>
+  ret <2 x float> %r
+}
+
+define <2 x float> @vtrn2(<2 x i32> %x, <2 x i32> %y) {
+; CHECK-LABEL: @vtrn2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[R_UNCASTED:%.*]] = shufflevector <2 x i32> [[X:%.*]], <2 x i32> [[Y:%.*]], <2 x i32> <i32 1, i32 3>
+; CHECK-NEXT:    [[R:%.*]] = bitcast <2 x i32> [[R_UNCASTED]] to <2 x float>
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+entry:
+  %xb = bitcast <2 x i32> %x to <2 x float>
+  %yb = bitcast <2 x i32> %y to <2 x float>
+  %r = shufflevector <2 x float> %xb, <2 x float> %yb, <2 x i32> <i32 1, i32 3>
+  ret <2 x float> %r
+}
+
+
+define <4 x float> @bc_shuf_lenchange(<2 x i32> %x, <2 x i32> %y) {
+; CHECK-LABEL: @bc_shuf_lenchange(
+; CHECK-NEXT:    [[R_UNCASTED:%.*]] = shufflevector <2 x i32> [[X:%.*]], <2 x i32> [[Y:%.*]], <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT:    [[R:%.*]] = bitcast <4 x i32> [[R_UNCASTED]] to <4 x float>
+; CHECK-NEXT:    ret <4 x float> [[R]]
+;
+  %xb = bitcast <2 x i32> %x to <2 x float>
+  %yb = bitcast <2 x i32> %y to <2 x float>
+  %r = shufflevector <2 x float> %xb, <2 x float> %yb, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+  ret <4 x float> %r
+}
+
+
+define <4 x float> @bc_shuf_nonvec(i64 %x, i64 %y) {
+; CHECK-LABEL: @bc_shuf_nonvec(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast i64 [[X:%.*]] to <2 x float>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast i64 [[Y:%.*]] to <2 x float>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <2 x float> [[XB]], <2 x float> [[YB]], <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT:    ret <4 x float> [[R]]
+;
+  %xb = bitcast i64 %x to <2 x float>
+  %yb = bitcast i64 %y to <2 x float>
+  %r = shufflevector <2 x float> %xb, <2 x float> %yb, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+  ret <4 x float> %r
+}
+
+define <4 x double> @bc_shuf_size(<4 x i32> %x, <4 x i32> %y) {
+; CHECK-LABEL: @bc_shuf_size(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <4 x i32> [[X:%.*]] to <2 x double>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast <4 x i32> [[Y:%.*]] to <2 x double>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <2 x double> [[XB]], <2 x double> [[YB]], <4 x i32> <i32 1, i32 3, i32 0, i32 2>
+; CHECK-NEXT:    ret <4 x double> [[R]]
+;
+  %xb = bitcast <4 x i32> %x to <2 x double>
+  %yb = bitcast <4 x i32> %y to <2 x double>
+  %r = shufflevector <2 x double> %xb, <2 x double> %yb, <4 x i32> <i32 1, i32 3, i32 0, i32 2>
+  ret <4 x double> %r
+}
+
+define <2 x double> @bc_shuf_mismatch(<4 x i32> %x, <2 x i64> %y) {
+; CHECK-LABEL: @bc_shuf_mismatch(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <4 x i32> [[X:%.*]] to <2 x double>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast <2 x i64> [[Y:%.*]] to <2 x double>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <2 x double> [[XB]], <2 x double> [[YB]], <2 x i32> <i32 1, i32 3>
+; CHECK-NEXT:    ret <2 x double> [[R]]
+;
+  %xb = bitcast <4 x i32> %x to <2 x double>
+  %yb = bitcast <2 x i64> %y to <2 x double>
+  %r = shufflevector <2 x double> %xb, <2 x double> %yb, <2 x i32> <i32 1, i32 3>
+  ret <2 x double> %r
+}
+
+define <8 x half> @bc_shuf_i8_float(<8 x i8> %x, <8 x i8> %y) {
+; CHECK-LABEL: @bc_shuf_i8_float(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <8 x i8> [[X:%.*]] to <4 x half>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast <8 x i8> [[Y:%.*]] to <4 x half>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <4 x half> [[XB]], <4 x half> [[YB]], <8 x i32> <i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4>
+; CHECK-NEXT:    ret <8 x half> [[R]]
+;
+  %xb = bitcast <8 x i8> %x to <4 x half>
+  %yb = bitcast <8 x i8> %y to <4 x half>
+  %r = shufflevector <4 x half> %xb, <4 x half> %yb, <8 x i32> <i32 3, i32 2, i32 1, i32 0, i32 7, i32 6, i32 5, i32 4>
+  ret <8 x half> %r
+}
+
+define <4 x i16> @bc_shuf_elemtype_mismatch(<2 x half> %x, <2 x bfloat> %y) {
+; CHECK-LABEL: @bc_shuf_elemtype_mismatch(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <2 x half> [[X:%.*]] to <2 x i16>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast <2 x bfloat> [[Y:%.*]] to <2 x i16>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <2 x i16> [[XB]], <2 x i16> [[YB]], <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+; CHECK-NEXT:    ret <4 x i16> [[R]]
+;
+  %xb = bitcast <2 x half> %x to <2 x i16>
+  %yb = bitcast <2 x bfloat> %y to <2 x i16>
+  %r = shufflevector <2 x i16> %xb, <2 x i16> %yb, <4 x i32> <i32 3, i32 2, i32 1, i32 0>
+  ret <4 x i16> %r
+}
+
+define <2 x float> @bc_shuf_reuse(<4 x i32> %x){
+; CHECK-LABEL: @bc_shuf_reuse(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <4 x i32> [[X:%.*]] to <4 x float>
+; CHECK-NEXT:    [[R:%.*]] = shufflevector <4 x float> [[XB]], <4 x float> undef, <2 x i32> zeroinitializer
+; CHECK-NEXT:    ret <2 x float> [[R]]
+;
+  %xb = bitcast <4 x i32> %x to <4 x float>
+  %r = shufflevector <4 x float> %xb, <4 x float> %xb, <2 x i32> <i32 0, i32 4>
+  ret <2 x float> %r
+}
+
+define <4 x float> @bc_shuf_y_hasoneuse(<4 x i32> %x, <4 x i32> %y){
+; CHECK-LABEL: @bc_shuf_y_hasoneuse(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <4 x i32> [[X:%.*]] to <4 x float>
+; CHECK-NEXT:    [[SHUF_UNCASTED:%.*]] = shufflevector <4 x i32> [[X]], <4 x i32> [[Y:%.*]], <4 x i32> <i32 0, i32 1, i32 4, i32 5>
+; CHECK-NEXT:    [[SHUF:%.*]] = bitcast <4 x i32> [[SHUF_UNCASTED]] to <4 x float>
+; CHECK-NEXT:    [[R:%.*]] = fadd <4 x float> [[XB]], [[SHUF]]
+; CHECK-NEXT:    ret <4 x float> [[R]]
+;
+  %xb = bitcast <4 x i32> %x to <4 x float>
+  %yb = bitcast <4 x i32> %y to <4 x float>
+  %shuf = shufflevector <4 x float> %xb, <4 x float> %yb, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
+  %r = fadd <4 x float> %xb, %shuf
+  ret <4 x float> %r
+}
+
+define <4 x float> @bc_shuf_neither_hasoneuse(<4 x i32> %x, <4 x i32> %y){
+; CHECK-LABEL: @bc_shuf_neither_hasoneuse(
+; CHECK-NEXT:    [[XB:%.*]] = bitcast <4 x i32> [[X:%.*]] to <4 x float>
+; CHECK-NEXT:    [[YB:%.*]] = bitcast <4 x i32> [[Y:%.*]] to <4 x float>
+; CHECK-NEXT:    [[SHUF:%.*]] = shufflevector <4 x float> [[XB]], <4 x float> undef, <4 x i32> <i32 0, i32 1, i32 0, i32 1>
+; CHECK-NEXT:    [[SUM:%.*]] = fadd <4 x float> [[XB]], [[YB]]
+; CHECK-NEXT:    [[R:%.*]] = fadd <4 x float> [[SUM]], [[SHUF]]
+; CHECK-NEXT:    ret <4 x float> [[R]]
+;
+  %xb = bitcast <4 x i32> %x to <4 x float>
+  %yb = bitcast <4 x i32> %y to <4 x float>
+  %shuf = shufflevector <4 x float> %xb, <4 x float> %xb, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
+  %sum = fadd <4 x float> %xb, %yb
+  %r = fadd <4 x float> %sum, %shuf
+  ret <4 x float> %r
+}