diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 908eee9..d1c732b 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -122,6 +122,7 @@
 
     shared_libs: [
         "android.hardware.graphics.common@1.1",
+        "libbase",
         "libsync",
         "libbinder",
         "libbufferhub",
diff --git a/libs/gui/FrameTimestamps.cpp b/libs/gui/FrameTimestamps.cpp
index 85ae433..96e9a85 100644
--- a/libs/gui/FrameTimestamps.cpp
+++ b/libs/gui/FrameTimestamps.cpp
@@ -18,10 +18,10 @@
 
 #define LOG_TAG "FrameEvents"
 
+#include <android-base/stringprintf.h>
 #include <cutils/compiler.h>  // For CC_[UN]LIKELY
 #include <inttypes.h>
 #include <utils/Log.h>
-#include <utils/String8.h>
 
 #include <algorithm>
 #include <limits>
@@ -29,6 +29,7 @@
 
 namespace android {
 
+using base::StringAppendF;
 
 // ============================================================================
 // FrameEvents
@@ -86,50 +87,49 @@
     releaseFence->getSignalTime();
 }
 
-static void dumpFenceTime(String8& outString, const char* name,
-        bool pending, const FenceTime& fenceTime) {
-    outString.appendFormat("--- %s", name);
+static void dumpFenceTime(std::string& outString, const char* name, bool pending,
+                          const FenceTime& fenceTime) {
+    StringAppendF(&outString, "--- %s", name);
     nsecs_t signalTime = fenceTime.getCachedSignalTime();
     if (Fence::isValidTimestamp(signalTime)) {
-        outString.appendFormat("%" PRId64 "\n", signalTime);
+        StringAppendF(&outString, "%" PRId64 "\n", signalTime);
     } else if (pending || signalTime == Fence::SIGNAL_TIME_PENDING) {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     } else if (&fenceTime == FenceTime::NO_FENCE.get()){
-        outString.appendFormat("N/A\n");
+        outString.append("N/A\n");
     } else {
-        outString.appendFormat("Error\n");
+        outString.append("Error\n");
     }
 }
 
-void FrameEvents::dump(String8& outString) const
-{
+void FrameEvents::dump(std::string& outString) const {
     if (!valid) {
         return;
     }
 
-    outString.appendFormat("-- Frame %" PRIu64 "\n", frameNumber);
-    outString.appendFormat("--- Posted      \t%" PRId64 "\n", postedTime);
-    outString.appendFormat("--- Req. Present\t%" PRId64 "\n", requestedPresentTime);
+    StringAppendF(&outString, "-- Frame %" PRIu64 "\n", frameNumber);
+    StringAppendF(&outString, "--- Posted      \t%" PRId64 "\n", postedTime);
+    StringAppendF(&outString, "--- Req. Present\t%" PRId64 "\n", requestedPresentTime);
 
-    outString.appendFormat("--- Latched     \t");
+    outString.append("--- Latched     \t");
     if (FrameEvents::isValidTimestamp(latchTime)) {
-        outString.appendFormat("%" PRId64 "\n", latchTime);
+        StringAppendF(&outString, "%" PRId64 "\n", latchTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
-    outString.appendFormat("--- Refresh (First)\t");
+    outString.append("--- Refresh (First)\t");
     if (FrameEvents::isValidTimestamp(firstRefreshStartTime)) {
-        outString.appendFormat("%" PRId64 "\n", firstRefreshStartTime);
+        StringAppendF(&outString, "%" PRId64 "\n", firstRefreshStartTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
-    outString.appendFormat("--- Refresh (Last)\t");
+    outString.append("--- Refresh (Last)\t");
     if (FrameEvents::isValidTimestamp(lastRefreshStartTime)) {
-        outString.appendFormat("%" PRId64 "\n", lastRefreshStartTime);
+        StringAppendF(&outString, "%" PRId64 "\n", lastRefreshStartTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
     dumpFenceTime(outString, "Acquire           \t",
@@ -139,11 +139,11 @@
     dumpFenceTime(outString, "Display Present   \t",
             !addPostCompositeCalled, *displayPresentFence);
 
-    outString.appendFormat("--- DequeueReady  \t");
+    outString.append("--- DequeueReady  \t");
     if (FrameEvents::isValidTimestamp(dequeueReadyTime)) {
-        outString.appendFormat("%" PRId64 "\n", dequeueReadyTime);
+        StringAppendF(&outString, "%" PRId64 "\n", dequeueReadyTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
     dumpFenceTime(outString, "Release           \t",
@@ -206,11 +206,11 @@
     return lhs.valid;
 }
 
-void FrameEventHistory::dump(String8& outString) const {
+void FrameEventHistory::dump(std::string& outString) const {
     auto earliestFrame = std::min_element(
             mFrames.begin(), mFrames.end(), &FrameNumberLessThan);
     if (!earliestFrame->valid) {
-        outString.appendFormat("-- N/A\n");
+        outString.append("-- N/A\n");
         return;
     }
     for (auto frame = earliestFrame; frame != mFrames.end(); ++frame) {
diff --git a/libs/gui/GuiConfig.cpp b/libs/gui/GuiConfig.cpp
index bc0c83c..3ec20ee 100644
--- a/libs/gui/GuiConfig.cpp
+++ b/libs/gui/GuiConfig.cpp
@@ -18,8 +18,7 @@
 
 namespace android {
 
-void appendGuiConfigString(String8& configStr)
-{
+void appendGuiConfigString(std::string& configStr) {
     static const char* config =
             " [libgui"
 #ifdef DONT_USE_FENCE_SYNC
diff --git a/libs/gui/LayerDebugInfo.cpp b/libs/gui/LayerDebugInfo.cpp
index ccde9e0..cdde9a2 100644
--- a/libs/gui/LayerDebugInfo.cpp
+++ b/libs/gui/LayerDebugInfo.cpp
@@ -16,13 +16,14 @@
 
 #include <gui/LayerDebugInfo.h>
 
+#include <android-base/stringprintf.h>
+
 #include <ui/DebugUtils.h>
 
 #include <binder/Parcel.h>
 
-#include <utils/String8.h>
-
 using namespace android;
+using android::base::StringAppendF;
 
 #define RETURN_ON_ERROR(X) do {status_t res = (X); if (res != NO_ERROR) return res;} while(false)
 
@@ -108,38 +109,37 @@
 }
 
 std::string to_string(const LayerDebugInfo& info) {
-    String8 result;
+    std::string result;
 
-    result.appendFormat("+ %s (%s)\n", info.mType.c_str(), info.mName.c_str());
+    StringAppendF(&result, "+ %s (%s)\n", info.mType.c_str(), info.mName.c_str());
     info.mTransparentRegion.dump(result, "TransparentRegion");
     info.mVisibleRegion.dump(result, "VisibleRegion");
     info.mSurfaceDamageRegion.dump(result, "SurfaceDamageRegion");
 
-    result.appendFormat("      layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), ",
-            info.mLayerStack, info.mZ, static_cast<double>(info.mX), static_cast<double>(info.mY),
-            info.mWidth, info.mHeight);
+    StringAppendF(&result, "      layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), ",
+                  info.mLayerStack, info.mZ, static_cast<double>(info.mX),
+                  static_cast<double>(info.mY), info.mWidth, info.mHeight);
 
-    result.appendFormat("crop=%s, ", to_string(info.mCrop).c_str());
-    result.appendFormat("isOpaque=%1d, invalidate=%1d, ", info.mIsOpaque, info.mContentDirty);
-    result.appendFormat("dataspace=%s, ", dataspaceDetails(info.mDataSpace).c_str());
-    result.appendFormat("pixelformat=%s, ", decodePixelFormat(info.mPixelFormat).c_str());
-    result.appendFormat("color=(%.3f,%.3f,%.3f,%.3f), flags=0x%08x, ",
-            static_cast<double>(info.mColor.r), static_cast<double>(info.mColor.g),
-            static_cast<double>(info.mColor.b), static_cast<double>(info.mColor.a),
-            info.mFlags);
-    result.appendFormat("tr=[%.2f, %.2f][%.2f, %.2f]",
-            static_cast<double>(info.mMatrix[0][0]), static_cast<double>(info.mMatrix[0][1]),
-            static_cast<double>(info.mMatrix[1][0]), static_cast<double>(info.mMatrix[1][1]));
+    StringAppendF(&result, "crop=%s, ", to_string(info.mCrop).c_str());
+    StringAppendF(&result, "isOpaque=%1d, invalidate=%1d, ", info.mIsOpaque, info.mContentDirty);
+    StringAppendF(&result, "dataspace=%s, ", dataspaceDetails(info.mDataSpace).c_str());
+    StringAppendF(&result, "pixelformat=%s, ", decodePixelFormat(info.mPixelFormat).c_str());
+    StringAppendF(&result, "color=(%.3f,%.3f,%.3f,%.3f), flags=0x%08x, ",
+                  static_cast<double>(info.mColor.r), static_cast<double>(info.mColor.g),
+                  static_cast<double>(info.mColor.b), static_cast<double>(info.mColor.a),
+                  info.mFlags);
+    StringAppendF(&result, "tr=[%.2f, %.2f][%.2f, %.2f]", static_cast<double>(info.mMatrix[0][0]),
+                  static_cast<double>(info.mMatrix[0][1]), static_cast<double>(info.mMatrix[1][0]),
+                  static_cast<double>(info.mMatrix[1][1]));
     result.append("\n");
-    result.appendFormat("      parent=%s\n", info.mParentName.c_str());
-    result.appendFormat("      activeBuffer=[%4ux%4u:%4u,%s],",
-            info.mActiveBufferWidth, info.mActiveBufferHeight,
-            info.mActiveBufferStride,
-            decodePixelFormat(info.mActiveBufferFormat).c_str());
-    result.appendFormat(" queued-frames=%d, mRefreshPending=%d",
-            info.mNumQueuedFrames, info.mRefreshPending);
+    StringAppendF(&result, "      parent=%s\n", info.mParentName.c_str());
+    StringAppendF(&result, "      activeBuffer=[%4ux%4u:%4u,%s],", info.mActiveBufferWidth,
+                  info.mActiveBufferHeight, info.mActiveBufferStride,
+                  decodePixelFormat(info.mActiveBufferFormat).c_str());
+    StringAppendF(&result, " queued-frames=%d, mRefreshPending=%d", info.mNumQueuedFrames,
+                  info.mRefreshPending);
     result.append("\n");
-    return std::string(result.c_str());
+    return result;
 }
 
 } // android
diff --git a/libs/gui/include/gui/FrameTimestamps.h b/libs/gui/include/gui/FrameTimestamps.h
index e06e40f..df02494 100644
--- a/libs/gui/include/gui/FrameTimestamps.h
+++ b/libs/gui/include/gui/FrameTimestamps.h
@@ -30,7 +30,6 @@
 
 struct FrameEvents;
 class FrameEventHistoryDelta;
-class String8;
 
 
 // Identifiers for all the events that may be recorded or reported.
@@ -72,7 +71,7 @@
     bool hasDequeueReadyInfo() const;
 
     void checkFencesForCompletion();
-    void dump(String8& outString) const;
+    void dump(std::string& outString) const;
 
     bool valid{false};
     int connectId{0};
@@ -112,7 +111,7 @@
     FrameEvents* getFrame(uint64_t frameNumber);
     FrameEvents* getFrame(uint64_t frameNumber, size_t* iHint);
     void checkFencesForCompletion();
-    void dump(String8& outString) const;
+    void dump(std::string& outString) const;
 
     static constexpr size_t MAX_FRAME_HISTORY = 8;
 
diff --git a/libs/gui/include/gui/GuiConfig.h b/libs/gui/include/gui/GuiConfig.h
index b020ed9..7aa5432 100644
--- a/libs/gui/include/gui/GuiConfig.h
+++ b/libs/gui/include/gui/GuiConfig.h
@@ -17,12 +17,12 @@
 #ifndef ANDROID_GUI_CONFIG_H
 #define ANDROID_GUI_CONFIG_H
 
-#include <utils/String8.h>
+#include <string>
 
 namespace android {
 
 // Append the libgui configuration details to configStr.
-void appendGuiConfigString(String8& configStr);
+void appendGuiConfigString(std::string& configStr);
 
 }; // namespace android
 
diff --git a/libs/gui/tests/Android.bp b/libs/gui/tests/Android.bp
index 6de641d..f020a40 100644
--- a/libs/gui/tests/Android.bp
+++ b/libs/gui/tests/Android.bp
@@ -37,6 +37,7 @@
     shared_libs: [
         "android.hardware.configstore@1.0",
         "android.hardware.configstore-utils",
+        "libbase",
         "liblog",
         "libEGL",
         "libGLESv1_CM",