diff --git a/WORKSPACE b/WORKSPACE
index 5e80a60b..d66021be 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -24,7 +24,7 @@ rules_foreign_cc_dependencies([
 git_repository(
     name = "io_opentracing_cpp",
     remote = "https://github.com/opentracing/opentracing-cpp",
-    commit = "ac50154a7713877f877981c33c3375003b6ebfe1",
+    commit = "4bb431f7728eaf383a07e86f9754a5b67575dab0",
 )
 
 git_repository(
diff --git a/ci/install_opentracing.sh b/ci/install_opentracing.sh
index 53a5674c..af875a26 100755
--- a/ci/install_opentracing.sh
+++ b/ci/install_opentracing.sh
@@ -2,7 +2,7 @@
 
 set -e
 
-[ -z "${OPENTRACING_VERSION}" ] && export OPENTRACING_VERSION="v1.5.0"
+[ -z "${OPENTRACING_VERSION}" ] && export OPENTRACING_VERSION="v1.6.0"
 
 # Build OpenTracing
 cd /
diff --git a/src/common/utility.cpp b/src/common/utility.cpp
index ac5a7213..20645cc9 100644
--- a/src/common/utility.cpp
+++ b/src/common/utility.cpp
@@ -145,6 +145,8 @@ struct JsonValueVisitor {
 
   void operator()(const char* s) { WriteEscapedString(writer, s); }
 
+  void operator()(opentracing::string_view s) { WriteEscapedString(writer, s); }
+
   void operator()(const opentracing::Values& values) {
     writer << '[';
     size_t i = 0;
diff --git a/src/tracer/legacy/BUILD b/src/tracer/legacy/BUILD
index 700f910e..95f8ec04 100644
--- a/src/tracer/legacy/BUILD
+++ b/src/tracer/legacy/BUILD
@@ -22,6 +22,7 @@ lightstep_cc_library(
         "//src/tracer:lightstep_span_context_interface",
         "//src/tracer:utility_lib",
         "//src/tracer:tag_lib",
+        ":legacy_immutable_span_context_lib",
     ],
 )
 
diff --git a/src/tracer/legacy/legacy_immutable_span_context.cpp b/src/tracer/legacy/legacy_immutable_span_context.cpp
index 5c41a5c4..8d8fd610 100644
--- a/src/tracer/legacy/legacy_immutable_span_context.cpp
+++ b/src/tracer/legacy/legacy_immutable_span_context.cpp
@@ -34,4 +34,17 @@ void LegacyImmutableSpanContext::ForeachBaggageItem(
     }
   }
 }
+
+//--------------------------------------------------------------------------------------------------
+// Clone
+//--------------------------------------------------------------------------------------------------
+std::unique_ptr<opentracing::SpanContext> LegacyImmutableSpanContext::Clone()
+    const noexcept try {
+  std::unique_ptr<opentracing::SpanContext> result{
+      new LegacyImmutableSpanContext{trace_id_, span_id_, sampled_,
+                                     BaggageProtobufMap{baggage_}}};
+  return result;
+} catch (const std::exception& /*e*/) {
+  return nullptr;
+}
 }  // namespace lightstep
diff --git a/src/tracer/legacy/legacy_immutable_span_context.h b/src/tracer/legacy/legacy_immutable_span_context.h
index 3cb0872e..f0b9c94f 100644
--- a/src/tracer/legacy/legacy_immutable_span_context.h
+++ b/src/tracer/legacy/legacy_immutable_span_context.h
@@ -18,6 +18,7 @@ class LegacyImmutableSpanContext final : public LightStepSpanContext {
 
   bool sampled() const noexcept override { return sampled_; }
 
+  // opentracing::SpanContext
   void ForeachBaggageItem(
       std::function<bool(const std::string& key, const std::string& value)> f)
       const override;
@@ -40,6 +41,8 @@ class LegacyImmutableSpanContext final : public LightStepSpanContext {
     return this->InjectImpl(propagation_options, writer);
   }
 
+  std::unique_ptr<opentracing::SpanContext> Clone() const noexcept override;
+
  private:
   uint64_t trace_id_;
   uint64_t span_id_;
diff --git a/src/tracer/legacy/legacy_span.cpp b/src/tracer/legacy/legacy_span.cpp
index 94f1398e..b2e6c0e8 100644
--- a/src/tracer/legacy/legacy_span.cpp
+++ b/src/tracer/legacy/legacy_span.cpp
@@ -2,6 +2,7 @@
 
 #include "common/random.h"
 #include "common/utility.h"
+#include "tracer/legacy/legacy_immutable_span_context.h"
 #include "tracer/tag.h"
 #include "tracer/utility.h"
 
@@ -227,8 +228,25 @@ std::string LegacySpan::BaggageItem(
 //------------------------------------------------------------------------------
 void LegacySpan::Log(std::initializer_list<
                      std::pair<opentracing::string_view, opentracing::Value>>
+                         fields) noexcept {
+  this->Log(SystemClock::now(), fields);
+}
+
+void LegacySpan::Log(opentracing::SystemTime timestamp,
+                     std::initializer_list<std::pair<opentracing::string_view,
+                                                     opentracing::Value>>
                          fields) noexcept try {
-  auto timestamp = SystemClock::now();
+  std::lock_guard<std::mutex> lock_guard{mutex_};
+  *span_.mutable_logs()->Add() =
+      ToLog(timestamp, std::begin(fields), std::end(fields));
+} catch (const std::exception& e) {
+  logger_.Error("Log failed: ", e.what());
+}
+
+void LegacySpan::Log(
+    opentracing::SystemTime timestamp,
+    const std::vector<std::pair<opentracing::string_view, opentracing::Value>>&
+        fields) noexcept try {
   std::lock_guard<std::mutex> lock_guard{mutex_};
   *span_.mutable_logs()->Add() =
       ToLog(timestamp, std::begin(fields), std::end(fields));
@@ -250,6 +268,21 @@ void LegacySpan::ForeachBaggageItem(
   }
 }
 
+//--------------------------------------------------------------------------------------------------
+// Clone
+//--------------------------------------------------------------------------------------------------
+std::unique_ptr<opentracing::SpanContext> LegacySpan::Clone() const
+    noexcept try {
+  std::lock_guard<std::mutex> lock_guard{mutex_};
+  std::unique_ptr<opentracing::SpanContext> result{
+      new LegacyImmutableSpanContext{
+          this->trace_id(), this->span_id(), sampled_,
+          BaggageProtobufMap{span_.span_context().baggage()}}};
+  return result;
+} catch (const std::exception& /*e*/) {
+  return nullptr;
+}
+
 //------------------------------------------------------------------------------
 // sampled
 //------------------------------------------------------------------------------
diff --git a/src/tracer/legacy/legacy_span.h b/src/tracer/legacy/legacy_span.h
index 779f7c71..f7340a01 100644
--- a/src/tracer/legacy/legacy_span.h
+++ b/src/tracer/legacy/legacy_span.h
@@ -44,6 +44,16 @@ class LegacySpan final : public opentracing::Span, public LightStepSpanContext {
            std::pair<opentracing::string_view, opentracing::Value>>
                fields) noexcept override;
 
+  void Log(opentracing::SystemTime timestamp,
+           std::initializer_list<
+               std::pair<opentracing::string_view, opentracing::Value>>
+               fields) noexcept override;
+
+  void Log(opentracing::SystemTime timestamp,
+           const std::vector<
+               std::pair<opentracing::string_view, opentracing::Value>>&
+               fields) noexcept override;
+
   const opentracing::SpanContext& context() const noexcept override {
     return *this;
   }
@@ -55,6 +65,8 @@ class LegacySpan final : public opentracing::Span, public LightStepSpanContext {
       std::function<bool(const std::string& key, const std::string& value)> f)
       const override;
 
+  std::unique_ptr<opentracing::SpanContext> Clone() const noexcept override;
+
   bool sampled() const noexcept override;
 
   uint64_t trace_id() const noexcept override {
diff --git a/src/tracer/lightstep_span_context.cpp b/src/tracer/lightstep_span_context.cpp
index d3231556..aedce003 100644
--- a/src/tracer/lightstep_span_context.cpp
+++ b/src/tracer/lightstep_span_context.cpp
@@ -1,6 +1,34 @@
 #include "tracer/lightstep_span_context.h"
 
+#include "common/utility.h"
+
 namespace lightstep {
+//--------------------------------------------------------------------------------------------------
+// ToHexString
+//--------------------------------------------------------------------------------------------------
+static std::string ToHexString(uint64_t x) {
+  std::array<char, Num64BitHexDigits> buffer;
+  return Uint64ToHex(x, buffer.data());
+}
+
+//--------------------------------------------------------------------------------------------------
+// ToTraceID
+//--------------------------------------------------------------------------------------------------
+std::string LightStepSpanContext::ToTraceID() const noexcept try {
+  return ToHexString(this->trace_id());
+} catch (const std::exception& /*e*/) {
+  return {};
+}
+
+//--------------------------------------------------------------------------------------------------
+// ToSpanID
+//--------------------------------------------------------------------------------------------------
+std::string LightStepSpanContext::ToSpanID() const noexcept try {
+  return ToHexString(this->span_id());
+} catch (const std::exception& /*e*/) {
+  return {};
+}
+
 //------------------------------------------------------------------------------
 // operator==
 //------------------------------------------------------------------------------
diff --git a/src/tracer/lightstep_span_context.h b/src/tracer/lightstep_span_context.h
index c3f4d890..d363bbc7 100644
--- a/src/tracer/lightstep_span_context.h
+++ b/src/tracer/lightstep_span_context.h
@@ -27,6 +27,10 @@ class LightStepSpanContext : public opentracing::SpanContext {
   virtual opentracing::expected<void> Inject(
       const PropagationOptions& propagation_options,
       const opentracing::HTTPHeadersWriter& writer) const = 0;
+
+  std::string ToTraceID() const noexcept final;
+
+  std::string ToSpanID() const noexcept final;
 };
 
 bool operator==(const LightStepSpanContext& lhs,
diff --git a/src/tracer/span.cpp b/src/tracer/span.cpp
index dc74999e..cdcb02c0 100644
--- a/src/tracer/span.cpp
+++ b/src/tracer/span.cpp
@@ -4,6 +4,7 @@
 
 #include "common/random.h"
 #include "common/utility.h"
+#include "tracer/legacy/legacy_immutable_span_context.h"
 #include "tracer/serialization.h"
 #include "tracer/tag.h"
 #include "tracer/utility.h"
@@ -157,7 +158,15 @@ std::string Span::BaggageItem(opentracing::string_view restricted_key) const
 void Span::Log(std::initializer_list<
                std::pair<opentracing::string_view, opentracing::Value>>
                    fields) noexcept try {
-  auto timestamp = SystemClock::now();
+  this->Log(SystemClock::now(), fields);
+} catch (const std::exception& e) {
+  tracer_->logger().Error("Log failed: ", e.what());
+}
+
+void Span::Log(opentracing::SystemTime timestamp,
+               std::initializer_list<
+                   std::pair<opentracing::string_view, opentracing::Value>>
+                   fields) noexcept try {
   SpinLockGuard lock_guard{mutex_};
   if (is_finished_) {
     return;
@@ -167,6 +176,19 @@ void Span::Log(std::initializer_list<
   tracer_->logger().Error("Log failed: ", e.what());
 }
 
+void Span::Log(
+    opentracing::SystemTime timestamp,
+    const std::vector<std::pair<opentracing::string_view, opentracing::Value>>&
+        fields) noexcept try {
+  SpinLockGuard lock_guard{mutex_};
+  if (is_finished_) {
+    return;
+  }
+  WriteLog(stream_, timestamp, fields.data(), fields.data() + fields.size());
+} catch (const std::exception& e) {
+  tracer_->logger().Error("Log failed: ", e.what());
+}
+
 //------------------------------------------------------------------------------
 // ForeachBaggageItem
 //------------------------------------------------------------------------------
@@ -181,6 +203,20 @@ void Span::ForeachBaggageItem(
   }
 }
 
+//--------------------------------------------------------------------------------------------------
+// Clone
+//--------------------------------------------------------------------------------------------------
+std::unique_ptr<opentracing::SpanContext> Span::Clone() const noexcept try {
+  SpinLockGuard lock_guard{mutex_};
+  BaggageProtobufMap baggage_copy{baggage_.begin(), baggage_.end()};
+  std::unique_ptr<opentracing::SpanContext> result{
+      new LegacyImmutableSpanContext{trace_id_, span_id_, sampled_,
+                                     std::move(baggage_copy)}};
+  return result;
+} catch (const std::exception& /*e*/) {
+  return nullptr;
+}
+
 //------------------------------------------------------------------------------
 // sampled
 //------------------------------------------------------------------------------
diff --git a/src/tracer/span.h b/src/tracer/span.h
index 658e1413..c29964c4 100644
--- a/src/tracer/span.h
+++ b/src/tracer/span.h
@@ -46,6 +46,16 @@ class Span final : public opentracing::Span, public LightStepSpanContext {
            std::pair<opentracing::string_view, opentracing::Value>>
                fields) noexcept override;
 
+  void Log(opentracing::SystemTime timestamp,
+           std::initializer_list<
+               std::pair<opentracing::string_view, opentracing::Value>>
+               fields) noexcept override;
+
+  void Log(opentracing::SystemTime timestamp,
+           const std::vector<
+               std::pair<opentracing::string_view, opentracing::Value>>&
+               fields) noexcept override;
+
   const opentracing::SpanContext& context() const noexcept override {
     return *this;
   }
@@ -76,6 +86,8 @@ class Span final : public opentracing::Span, public LightStepSpanContext {
     return this->InjectImpl(propagation_options, writer);
   }
 
+  std::unique_ptr<opentracing::SpanContext> Clone() const noexcept override;
+
   // LightStepSpanContext
   bool sampled() const noexcept override;
 
diff --git a/test/tracer/tracer_test.cpp b/test/tracer/tracer_test.cpp
index 1b31b43e..56a34de1 100644
--- a/test/tracer/tracer_test.cpp
+++ b/test/tracer/tracer_test.cpp
@@ -6,6 +6,7 @@
 #include "test/recorder/in_memory_recorder.h"
 #include "test/utility.h"
 #include "tracer/legacy/legacy_tracer_impl.h"
+#include "tracer/lightstep_span_context.h"
 #include "tracer/tag.h"
 #include "tracer/tracer_impl.h"
 
@@ -197,8 +198,12 @@ TEST_CASE("tracer") {
       auto span = tracer->StartSpan("a");
       REQUIRE(span);
       span->Log({{"abc", 123}});
+      span->Log(
+          std::chrono::system_clock::now(),
+          std::vector<std::pair<opentracing::string_view, opentracing::Value>>{
+              {"abc", 123}});
       span->Finish();
-      REQUIRE(recorder->top().logs().size() == 1);
+      REQUIRE(recorder->top().logs().size() == 2);
     }
 
     SECTION(tracer_type + ": Logs can be added with FinishSpanOptions.") {
@@ -219,6 +224,28 @@ TEST_CASE("tracer") {
       span->SetTag("abc", 123);
       span->Log({{"abc", 123}});
     }
+
+    SECTION(tracer_type + ": span contexts can be cloned") {
+      auto span = tracer->StartSpan("a");
+      REQUIRE(span);
+      span->SetBaggageItem("abc", "123");
+      auto span_context1 = span->context().Clone();
+      REQUIRE(span_context1 != nullptr);
+      auto span_context2 = span_context1->Clone();
+      REQUIRE(span_context2 != nullptr);
+      REQUIRE(dynamic_cast<const LightStepSpanContext&>(span->context()) ==
+              dynamic_cast<LightStepSpanContext&>(*span_context1));
+    }
+
+    SECTION(tracer_type + ": supports accessing context IDs as strings") {
+      auto span = tracer->StartSpan("a");
+      REQUIRE(span);
+      auto trace_id = span->context().ToTraceID();
+      REQUIRE(!trace_id.empty());
+      auto span_id = span->context().ToSpanID();
+      REQUIRE(!span_id.empty());
+      REQUIRE(trace_id != span_id);
+    }
   }
 }