diff --git a/runtime/interpreter/interpreter_intrinsics.cc b/runtime/interpreter/interpreter_intrinsics.cc
index 5e901cd..ff0c20e 100644
--- a/runtime/interpreter/interpreter_intrinsics.cc
+++ b/runtime/interpreter/interpreter_intrinsics.cc
@@ -79,6 +79,151 @@
 // java.lang.Math.atan(D)D
 UNARY_SIMPLE_INTRINSIC(MterpMathAtan, std::atan, GetVRegDouble, SetD);
 
+// java.lang.String.charAt(I)C
+static ALWAYS_INLINE bool MterpStringCharAt(ShadowFrame* shadow_frame,
+                                            const Instruction* inst,
+                                            uint16_t inst_data,
+                                            JValue* result_register)
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};
+  inst->GetVarArgs(arg, inst_data);
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString();
+  int length = str->GetLength();
+  int index = shadow_frame->GetVReg(arg[1]);
+  uint16_t res;
+  if (UNLIKELY(index < 0) || (index >= length)) {
+    return false;  // Punt and let non-intrinsic version deal with the throw.
+  }
+  if (str->IsCompressed()) {
+    res = str->GetValueCompressed()[index];
+  } else {
+    res = str->GetValue()[index];
+  }
+  result_register->SetC(res);
+  return true;
+}
+
+// java.lang.String.compareTo(Ljava/lang/string)I
+static ALWAYS_INLINE bool MterpStringCompareTo(ShadowFrame* shadow_frame,
+                                               const Instruction* inst,
+                                               uint16_t inst_data,
+                                               JValue* result_register)
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};
+  inst->GetVarArgs(arg, inst_data);
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString();
+  mirror::Object* arg1 = shadow_frame->GetVRegReference(arg[1]);
+  if (arg1 == nullptr) {
+    return false;
+  }
+  result_register->SetI(str->CompareTo(arg1->AsString()));
+  return true;
+}
+
+#define STRING_INDEXOF_INTRINSIC(name, starting_pos)             \
+static ALWAYS_INLINE bool Mterp##name(ShadowFrame* shadow_frame, \
+                                      const Instruction* inst,   \
+                                      uint16_t inst_data,        \
+                                      JValue* result_register)   \
+    REQUIRES_SHARED(Locks::mutator_lock_) {                      \
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};                \
+  inst->GetVarArgs(arg, inst_data);                              \
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString(); \
+  int ch = shadow_frame->GetVReg(arg[1]);                        \
+  if (ch >= 0x10000) {                                           \
+    /* Punt if supplementary char. */                            \
+    return false;                                                \
+  }                                                              \
+  result_register->SetI(str->FastIndexOf(ch, starting_pos));     \
+  return true;                                                   \
+}
+
+// java.lang.String.indexOf(I)I
+STRING_INDEXOF_INTRINSIC(StringIndexOf, 0);
+
+// java.lang.String.indexOf(II)I
+STRING_INDEXOF_INTRINSIC(StringIndexOfAfter, shadow_frame->GetVReg(arg[2]));
+
+#define SIMPLE_STRING_INTRINSIC(name, operation)                 \
+static ALWAYS_INLINE bool Mterp##name(ShadowFrame* shadow_frame, \
+                                      const Instruction* inst,   \
+                                      uint16_t inst_data,        \
+                                      JValue* result_register)   \
+    REQUIRES_SHARED(Locks::mutator_lock_) {                      \
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};                \
+  inst->GetVarArgs(arg, inst_data);                              \
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString(); \
+  result_register->operation;                                    \
+  return true;                                                   \
+}
+
+// java.lang.String.isEmpty()Z
+SIMPLE_STRING_INTRINSIC(StringIsEmpty, SetZ(str->GetLength() == 0))
+
+// java.lang.String.length()I
+SIMPLE_STRING_INTRINSIC(StringLength, SetI(str->GetLength()))
+
+// java.lang.String.getCharsNoCheck(II[CI)V
+static ALWAYS_INLINE bool MterpStringGetCharsNoCheck(ShadowFrame* shadow_frame,
+                                                     const Instruction* inst,
+                                                     uint16_t inst_data,
+                                                     JValue* result_register ATTRIBUTE_UNUSED)
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  // Start, end & index already checked by caller - won't throw.  Destination is uncompressed.
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};
+  inst->GetVarArgs(arg, inst_data);
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString();
+  int32_t start = shadow_frame->GetVReg(arg[1]);
+  int32_t end = shadow_frame->GetVReg(arg[2]);
+  int32_t index = shadow_frame->GetVReg(arg[4]);
+  mirror::CharArray* array = shadow_frame->GetVRegReference(arg[3])->AsCharArray();
+  uint16_t* dst = array->GetData() + index;
+  int32_t len = (end - start);
+  if (str->IsCompressed()) {
+    const uint8_t* src_8 = str->GetValueCompressed() + start;
+    for (int i = 0; i < len; i++) {
+      dst[i] = src_8[i];
+    }
+  } else {
+    uint16_t* src_16 = str->GetValue() + start;
+    memcpy(dst, src_16, len * sizeof(uint16_t));
+  }
+  return true;
+}
+
+// java.lang.String.equalsLjava/lang/Object;)Z
+static ALWAYS_INLINE bool MterpStringEquals(ShadowFrame* shadow_frame,
+                                            const Instruction* inst,
+                                            uint16_t inst_data,
+                                            JValue* result_register)
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  uint32_t arg[Instruction::kMaxVarArgRegs] = {};
+  inst->GetVarArgs(arg, inst_data);
+  mirror::String* str = shadow_frame->GetVRegReference(arg[0])->AsString();
+  mirror::Object* obj = shadow_frame->GetVRegReference(arg[1]);
+  bool res = false;  // Assume not equal.
+  if ((obj != nullptr) && obj->IsString()) {
+    mirror::String* str2 = obj->AsString();
+    if (str->GetCount() == str2->GetCount()) {
+      // Length & compression status are same.  Can use block compare.
+      void* bytes1;
+      void* bytes2;
+      int len = str->GetLength();
+      if (str->IsCompressed()) {
+        bytes1 = str->GetValueCompressed();
+        bytes2 = str2->GetValueCompressed();
+      } else {
+        len *= sizeof(uint16_t);
+        bytes1 = str->GetValue();
+        bytes2 = str2->GetValue();
+      }
+      res = (memcmp(bytes1, bytes2, len) == 0);
+    }
+  }
+  result_register->SetZ(res);
+  return true;
+}
+
 #define INTRINSIC_CASE(name)                                           \
     case Intrinsics::k##name:                                          \
       res = Mterp##name(shadow_frame, inst, inst_data, result_register); \
@@ -110,6 +255,14 @@
     INTRINSIC_CASE(MathAsin)
     INTRINSIC_CASE(MathAcos)
     INTRINSIC_CASE(MathAtan)
+    INTRINSIC_CASE(StringCharAt)
+    INTRINSIC_CASE(StringCompareTo)
+    INTRINSIC_CASE(StringIndexOf)
+    INTRINSIC_CASE(StringIndexOfAfter)
+    INTRINSIC_CASE(StringEquals)
+    INTRINSIC_CASE(StringGetCharsNoCheck)
+    INTRINSIC_CASE(StringIsEmpty)
+    INTRINSIC_CASE(StringLength)
     default:
       res = false;  // Punt
       break;
diff --git a/runtime/jvalue.h b/runtime/jvalue.h
index 398bfbc..f61a07c 100644
--- a/runtime/jvalue.h
+++ b/runtime/jvalue.h
@@ -39,7 +39,9 @@
   }
 
   uint16_t GetC() const { return c; }
-  void SetC(uint16_t new_c) { c = new_c; }
+  void SetC(uint16_t new_c) {
+    j = static_cast<int64_t>(new_c);  // Zero-extend to 64 bits.
+  }
 
   double GetD() const { return d; }
   void SetD(double new_d) { d = new_d; }
@@ -66,7 +68,9 @@
   }
 
   uint8_t GetZ() const { return z; }
-  void SetZ(uint8_t new_z) { z = new_z; }
+  void SetZ(uint8_t new_z) {
+    j = static_cast<int64_t>(new_z);  // Zero-extend to 64 bits.
+  }
 
   mirror::Object** GetGCRoot() { return &l; }