diff --git a/src/alloy/backend/x64/lowering/lowering_sequences.cc b/src/alloy/backend/x64/lowering/lowering_sequences.cc
index 2607c4495..8f3b2599f 100644
--- a/src/alloy/backend/x64/lowering/lowering_sequences.cc
+++ b/src/alloy/backend/x64/lowering/lowering_sequences.cc
@@ -63,6 +63,7 @@ enum XmmConst {
   XMMSignMaskPS         = 8,
   XMMSignMaskPD         = 9,
   XMMByteSwapMask       = 10,
+  XMMPermuteControl15   = 11,
 };
 static const vec128_t xmm_consts[] = {
   /* XMMZero                */ vec128f(0.0f, 0.0f, 0.0f, 0.0f),
@@ -76,6 +77,7 @@ static const vec128_t xmm_consts[] = {
   /* XMMSignMaskPS          */ vec128i(0x80000000u, 0x80000000u, 0x80000000u, 0x80000000u),
   /* XMMSignMaskPD          */ vec128i(0x00000000u, 0x80000000u, 0x00000000u, 0x80000000u),
   /* XMMByteSwapMask        */ vec128i(0x00010203u, 0x04050607u, 0x08090A0Bu, 0x0C0D0E0Fu),
+  /* XMMPermuteControl15    */ vec128b(15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15),
 };
 // Use consts by first loading the base register then accessing memory:
 // e.mov(e.rax, XMMCONSTBASE)
@@ -84,6 +86,45 @@ static const vec128_t xmm_consts[] = {
 #define XMMCONSTBASE (uint64_t)&xmm_consts[0]
 #define XMMCONST(base_reg, name) e.ptr[base_reg + name * 16]
 
+static vec128_t lvsl_table[17] = {
+  vec128b( 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15),
+  vec128b( 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16),
+  vec128b( 2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17),
+  vec128b( 3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18),
+  vec128b( 4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19),
+  vec128b( 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20),
+  vec128b( 6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21),
+  vec128b( 7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22),
+  vec128b( 8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23),
+  vec128b( 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24),
+  vec128b(10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25),
+  vec128b(11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26),
+  vec128b(12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27),
+  vec128b(13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28),
+  vec128b(14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29),
+  vec128b(15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30),
+  vec128b(16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31),
+};
+static vec128_t lvsr_table[17] = {
+  vec128b(16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31),
+  vec128b(15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30),
+  vec128b(14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29),
+  vec128b(13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28),
+  vec128b(12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27),
+  vec128b(11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26),
+  vec128b(10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25),
+  vec128b( 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24),
+  vec128b( 8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23),
+  vec128b( 7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22),
+  vec128b( 6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21),
+  vec128b( 5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20),
+  vec128b( 4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19),
+  vec128b( 3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18),
+  vec128b( 2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17),
+  vec128b( 1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16),
+  vec128b( 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15),
+};
+
 // A note about vectors:
 // Alloy represents vectors as xyzw pairs, with indices 0123.
 // XMM registers are xyzw pairs with indices 3210, making them more like wzyx.
@@ -792,14 +833,56 @@ table->AddSequence(OPCODE_VECTOR_CONVERT_F2I, [](X64Emitter& e, Instr*& i) {
 
 table->AddSequence(OPCODE_LOAD_VECTOR_SHL, [](X64Emitter& e, Instr*& i) {
   XEASSERT(i->dest->type == VEC128_TYPE);
-  UNIMPLEMENTED_SEQ();
+  if (i->src1.value->IsConstant()) {
+    Xmm dest;
+    e.BeginOp(i->dest, dest, REG_DEST);
+    auto sh = MIN(16, i->src1.value->AsUint32());
+    e.mov(e.rax, (uintptr_t)&lvsl_table[sh]);
+    e.movaps(dest, e.ptr[e.rax]);
+    e.EndOp(dest);
+  } else {
+    Xmm dest;
+    Reg8 src;
+    e.BeginOp(i->dest, dest, REG_DEST,
+              i->src1.value, src, 0);
+    // TODO(benvanik): probably a way to do this with addressing.
+    e.mov(TEMP_REG, 16);
+    e.movzx(e.rax, src);
+    e.cmp(src, 16);
+    e.cmovb(TEMP_REG, e.rax);
+    e.shl(TEMP_REG, 4);
+    e.mov(e.rax, (uintptr_t)lvsl_table);
+    e.movaps(dest, e.ptr[e.rax + TEMP_REG]);
+    e.EndOp(dest, src);
+  }
   i = e.Advance(i);
   return true;
 });
 
 table->AddSequence(OPCODE_LOAD_VECTOR_SHR, [](X64Emitter& e, Instr*& i) {
   XEASSERT(i->dest->type == VEC128_TYPE);
-  UNIMPLEMENTED_SEQ();
+  if (i->src1.value->IsConstant()) {
+    Xmm dest;
+    e.BeginOp(i->dest, dest, REG_DEST);
+    auto sh = MIN(16, i->src1.value->AsUint32());
+    e.mov(e.rax, (uintptr_t)&lvsr_table[sh]);
+    e.movaps(dest, e.ptr[e.rax]);
+    e.EndOp(dest);
+  } else {
+    Xmm dest;
+    Reg8 src;
+    e.BeginOp(i->dest, dest, REG_DEST,
+              i->src1.value, src, 0);
+    // TODO(benvanik): probably a way to do this with addressing.
+    e.mov(TEMP_REG, 16);
+    e.movzx(e.rax, src);
+    e.cmp(src, 16);
+    e.cmovb(TEMP_REG, e.rax);
+    e.shl(TEMP_REG, 4);
+    e.mov(e.rax, (uintptr_t)lvsr_table);
+    e.movaps(dest, e.ptr[e.rax + TEMP_REG]);
+    e.EndOp(dest, src);
+  }
   i = e.Advance(i);
   return true;
 });
diff --git a/src/alloy/backend/x64/lowering/op_utils.inl b/src/alloy/backend/x64/lowering/op_utils.inl
index da28030c5..94aaaef72 100644
--- a/src/alloy/backend/x64/lowering/op_utils.inl
+++ b/src/alloy/backend/x64/lowering/op_utils.inl
@@ -51,6 +51,12 @@ Address Stash(X64Emitter& e, const Xmm& r) {
   return addr;
 }
 
+void LoadXmmConstant(X64Emitter& e, Xmm& dest, const vec128_t& v) {
+  e.mov(e.qword[e.rsp + STASH_OFFSET], v.low);
+  e.mov(e.qword[e.rsp + STASH_OFFSET + 8], v.high);
+  e.movaps(dest, e.ptr[e.rsp + STASH_OFFSET]);
+}
+
 // Moves a 64bit immediate into memory.
 void MovMem64(X64Emitter& e, RegExp& addr, uint64_t v) {
   if ((v & ~0x7FFFFFFF) == 0) {
diff --git a/src/alloy/core.h b/src/alloy/core.h
index cd7a32204..aef7e57c2 100644
--- a/src/alloy/core.h
+++ b/src/alloy/core.h
@@ -55,6 +55,18 @@ XEFORCEINLINE vec128_t vec128f(float x, float y, float z, float w) {
   v.f4[0] = x; v.f4[1] = y; v.f4[2] = z; v.f4[3] = w;
   return v;
 }
+XEFORCEINLINE vec128_t vec128b(
+    uint8_t x0, uint8_t x1, uint8_t x2, uint8_t x3,
+    uint8_t y0, uint8_t y1, uint8_t y2, uint8_t y3,
+    uint8_t z0, uint8_t z1, uint8_t z2, uint8_t z3,
+    uint8_t w0, uint8_t w1, uint8_t w2, uint8_t w3) {
+  vec128_t v;
+  v.b16[0]  = x3; v.b16[1]  = x2; v.b16[2]  = x1; v.b16[3]  = x0;
+  v.b16[4]  = y3; v.b16[5]  = y2; v.b16[6]  = y1; v.b16[7]  = y0;
+  v.b16[8]  = z3; v.b16[9]  = z2; v.b16[10] = z1; v.b16[11] = z0;
+  v.b16[12] = w3; v.b16[13] = w2; v.b16[14] = w1; v.b16[15] = w0;
+  return v;
+}
 
 }  // namespace alloy
 
diff --git a/src/alloy/hir/value.h b/src/alloy/hir/value.h
index 37a0a4a5a..4fa957932 100644
--- a/src/alloy/hir/value.h
+++ b/src/alloy/hir/value.h
@@ -184,25 +184,26 @@ public:
   }
   bool IsConstantTrue() const {
     if (type == VEC128_TYPE) {
-      return false;
+      XEASSERTALWAYS();
     }
     return (flags & VALUE_IS_CONSTANT) && !!constant.i64;
   }
   bool IsConstantFalse() const {
     if (type == VEC128_TYPE) {
-      return false;
+      XEASSERTALWAYS();
     }
     return (flags & VALUE_IS_CONSTANT) && !constant.i64;
   }
   bool IsConstantZero() const {
     if (type == VEC128_TYPE) {
-      return false;
+      return (flags & VALUE_IS_CONSTANT) &&
+             !constant.v128.low && !constant.v128.high;
     }
     return (flags & VALUE_IS_CONSTANT) && !constant.i64;
   }
   bool IsConstantEQ(Value* other) const {
     if (type == VEC128_TYPE) {
-      return false;
+      XEASSERTALWAYS();
     }
     return (flags & VALUE_IS_CONSTANT) &&
            (other->flags & VALUE_IS_CONSTANT) &&
@@ -210,7 +211,7 @@ public:
   }
   bool IsConstantNE(Value* other) const {
     if (type == VEC128_TYPE) {
-      return false;
+      XEASSERTALWAYS();
     }
     return (flags & VALUE_IS_CONSTANT) &&
            (other->flags & VALUE_IS_CONSTANT) &&